Cutting attachment for a surgical handpiece designed to be selectively coupled to the handpiece

ABSTRACT

A cutting accessory ( 40   a ) for use with a powered surgical tool. The cutting accessory includes a head ( 42 ) with a cutting surface that is applied to a surgical site and a shaft ( 44   a ) that extends from the head. A plurality of retention features ( 530 ) are formed on the shaft. This makes it possible to longitudinally adjust the position of the cutting accessory relative to the tool with which the accessory is used. The interstitial sections of the shaft located between the retention features have an asymmetric profile relative to the longitudinal axis of the shaft. This facilitates the auto-alignment of the cutting accessory to a handpiece when clamping members integral to the handpiece are pressed against the accessory.

RELATIONSHIP TO EARLIER FILED APPLICATION

[0001] This application claims priority under 35 U.S.C. Sec. 119 fromU.S. Provisional Application No. 60/183 766, filed Feb. 18, 2000. Thisapplication is a continuation-in-part of the '766 Application.

FIELD OF THE INVENTION

[0002] This invention relates generally to a surgical tool system towhich cutting accessories are selectively attached. More particularly,this invention relates to a surgical tool system and a complementarycutting accessory that are collectively configured to allow thelongitudinal position of the cutting accessory relative the handpiece tobe selectively set.

BACKGROUND OF THE INVENTION

[0003] In modern surgery one of the most important instruments availableto medical personnel is the powered surgical tool. Typically, this toolcomprises some type of handpiece in which a motor is housed. Secured tothe handpiece is a cutting accessory designed for application to asurgical site on a patient in order to accomplish a specific medicaltask. Some powered surgical tools are provided with drills or burrs forcutting bores into hard tissue or for selectively removing the hardtissue. Still other powered surgical tools are provided with saw bladesas cutting accessories. These tools are used for separating largesections of hard and/or soft tissue. The ability to use powered surgicaltools on a patient has lessened the physical strain of physicians andother medical personnel when performing procedures on a patient.Moreover, most surgical procedures can be performed more quickly, andmore accurately, with powered surgical tools than with the manualequivalents that preceded them.

[0004] The Applicant's U.S. Pat. No. 5,888,200, entitled, MULTI-PURPOSESURGICAL TOOL SYSTEM, issued Mar. 30, 1999, incorporated herein byreference, discloses a surgical tool system designed for a number ofdifferent applications. This tool system includes a handpiece in which amotor is housed. The handpiece also includes a first coupling assemblyfor selectively coupling the shaft of a cutting accessory to the motorshaft. This handpiece also includes a second coupling assembly. Thesecond coupling assembly is used to selectively secure an attachment tothe front end of the handpiece. This attachment may include its owndrive shaft and accessory coupling assembly. These attachments areelongated attachments, angled attachments and/or able to actuate sawblades. Thus, an advantage of providing this type of tool system is thata single handpiece can be used to drive a large number of differentcutting accessories and facilitate the positioning of the accessories atthe surgical site in a manner that is either required or desired for aparticular surgical procedure.

[0005] Popular cutting accessories that are used with this type ofsurgical tool system include drills and burs. Each of these cuttingaccessories typically has a head that forms the actual tissue removalmember of the accessory. A shaft extends rearwardly from the head. Theshaft is the component of the cutting accessory against which thecoupling assembly locks.

[0006] There is a limitation associated with the above-described system.The coupling assembly of this system is designed so that a cuttingaccessory can only be secured to it in a single, fixed location relativeto the handpiece. A disadvantage of this arrangement is that surgeonsfrequently find it useful to have some degree of flexibility inpositioning the head of the cutting accessory relative to the handpiece.To date, to offer this flexibility, it is necessary to provide a set ofcutting accessories that have identical cutting heads. The differencebetween the accessories is the length of their complementary shafts.When a surgeon wants the head of the accessory to be positionedrelatively close to the handpiece, he/she installs in the handpiece acutting accessory with a shaft that is relatively short in length. Ifthe surgeon wants the head of the accessory to be spaced a distance fromthe handpiece, he/she installs in the handpiece a cutting accessory thathas a relatively long shaft.

[0007] Moreover, during a surgical procedure, a surgeon may want to usedifferent tools to access different locations at the surgical site.Alternatively, surgeons have individual preferences regarding how theywant to view a surgical site and/or handle their surgical tools. Inorder to accommodate these variations, surgical tool systems areprovided wit members that vary in only the geometry and/or dimensions ofthe components employed to transfer the power developed by the handpiecemotor to the associated cutting accessory. For example, the tool systemdescribed in the above-referenced U.S. Pat. No. 5,888,200 has differentlength attachments and attachments that have distal end sections thatare straight and angled from the associated handpiece housing. Ifsurgeon has to access a surgical site located close to the skin of thepatient he/she has available a medium length attachment. Alternatively,if the surgeon has to access a surgical site deep within the patient,the surgeon has available a long attachment. This attachment, incomparison to the medium length attachment, holds the head of thecutting accessory a relatively long distance away from handpiece. Angledattachments are also available. These attachments are used to nold thecutting accessory at an angle that is offset to the longitudinal axis ofthe handpiece. Angled attachments are used to position the cuttingaccessory at surgical sites that are difficult to reach and/or toprovide a surgeon with an alternative field of view of the surgicalsite.

[0008] Clearly, having these different attachments available isbeneficial to the surgeon. However, the coupling assemblies internal tothese attachments are often located different longitudinal distancesfrom their head ends, theirs distal ends, the ends from which the shaftof the accessory emerges. In order to use these attachments, it isnecessary to provide cutting accessories with the same head but thathave different length shafts. Accessories with short length shafts arefitted into attachments in which the coupling assemblies are positionedrelatively short distances from their distal end openings. Accessorieswith long length shafts are fitted into attachments in which thecoupling assemblies are positioned longer distances from their distalend openings. This is another reason why it is sometimes necessary tohave a number of different cutting accessories available for use in asingle surgical procedure that vary only in their shaft length.

[0009] Another limitation associated with cutting accessories such asdrills and burs is related to the fact that sometimes a number ofdifferent accessories are packaged as a set. These accessories are sopackaged together because a surgeon, during a procedure, may want toview the complete set of accessories he/she has available for use.Alternatively, prior to the beginning of a surgical procedure, a numberof individual accessories are each unpackaged and arranged as a set forthe surgeon. Again, this is to allow the surgeon to both view and haveeasy access to a number of different accessories.

[0010] However, often, during a procedure, the surgeon does not use allof the cutting accessories that have been unwrapped from their sterilepackaging. The accessories that are used are typically discarded. Thisis because the cutting heads of these accessories are at least partiallyworn. However, after the procedure, there may be one or more exposedcutting accessories that were not used. These accessories can be used ina new procedure, if prior to reuse they are sterilized to remove anycontaminates they may have picked up as a result of their exposure tothe environment. In a procedure used to sterilize these accessories theyare heated to a temperature of approximately 132° C., and subjected tosaturated water vapor at a pressure of 2.1 bars. These accessories areformed of tool steel because cutting surfaces formed from this materialtends to wear at a slower rate cutting surfaces formed from stainlesssteel. Also, tool steel is less expensive than an alternative material,carbide steel. However, during the above-described sterilizationprocess, the tool steel tends to discolor. This discoloration isdisconcerting to medical personnel. Consequently, medical personnel arereluctant to use these unused autoclave-sterilized accessories eventhough their quality and the degree of sterilization is the same asaccessories that have just been removed from the manufacturer'spackaging. Thus, there is tendency to discard these unused accessorieseven though, with proper sterilization, that can be available for use ina later procedure. The discarding of these cutting accessories, eventhough they have not even been used, is a waste of resources.

SUMMARY OF THE INVENTION

[0011] This invention relates to a new and useful surgical tool system.The surgical tool system of this invention includes a handpiece with acoupling assembly and complementary cutting accessories that aredesigned to fit the handpiece. Collectively, the coupling assembly andthe cutting accessories are designed so that the longitudinal extent towhich the cutting accessories extend out of the coupling assembly can beselectively set. Still a further feature of the surgical tool system ofthis invention is that though system has different length attachments,the coupling assemblies internal to these attachments are collectivelydesigned so that a cutting accessory having a single length shaft, acommon length shaft, can be used with each attachment.

[0012] Another feature of the surgical tool system of this invention isthat the cutting accessories are fabricated so that, as long as theaccessories are not used in a surgical procedure, the accessories can beexposed to autoclave sterilization without corroding.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention is pointed out with particularity in the claims.The above and further features of this invention may be betterunderstood by reference to the following description taken inconjunction with the accompanying drawings, in which:

[0014]FIG. 1 is plan view of the basic components of the tool system ofthis invention;

[0015]FIG. 2 is a cross-sectional view of the attachment of the toolsystem of this invention that contains the coupling assembly;

[0016]FIG. 3 is an enlarged cross-sectional view of the couplingassembly;

[0017]FIGS. 4A and 4B are, respectively, perspective and cross-sectionalviews of the input drive shaft;

[0018]FIGS. 5A and 5B are, respectively top and cross-sectional views ofthe output drive shaft;

[0019]FIG. 6 is an exploded view of the inner components that form thecoupling assembly;

[0020]FIG. 7 is a cross-sectional view of the actuator of the couplingassembly;

[0021]FIG. 8 is an exploded view of the outer component of the couplingassembly;

[0022]FIG. 8A is a plan view depicting the shape of one of the slotsformed in the attachment housing;

[0023]FIG. 8B is a perspective view of a collar;

[0024]FIG. 9 is a perspective view of the shaft of a cutting accessoryof this invention;

[0025]FIG. 10 is a plan view of the shaft of FIG. 9;

[0026]FIG. 11 is an end view of the shaft of FIG. 9;

[0027]FIGS. 12A and 12B are cross-sectional views depicting how, as aresult of an initial radial displacement of the collet legs and feet,the collet sleeve blocks further displacement of the collet legs andfeet;

[0028]FIG. 13 is a perspective view of an alternative attachment of thesystem of this invention;

[0029]FIG. 14 is a cross-sectional view of the attachment of FIG. 13;

[0030]FIG. 15 is an enlarged cross-sectional view of the attachment ofFIG. 13 in which the components forming the coupling assembly internalto the attachment are depicted;

[0031]FIGS. 16A and 16B are, respectively, perspective and cross-sectionviews of the input drive shaft of the attachment of FIG. 13;

[0032]FIG. 17 is a plan view of the output drive shaft of the attachmentof FIG. 13;

[0033]FIG. 18 is an exploded view of how the forward components of thecoupling assembly of the drive shaft of FIG. 12 cooperate;

[0034]FIG. 19 is a cross-sectional view of the collet sleeve of thecoupling assembly of FIG. 13;

[0035]FIG. 20 is a plan view of the push rod of the coupling assembly ofFIG. 12;

[0036]FIGS. 21A and 21B are cross-sectional views depicting how, as aresult of an initial radial displacement of the collet legs and feet ofthe coupling assembly of FIG. 12, the collet sleeve blocks furtherdisplacement of the collet legs and feet;

[0037]FIG. 22 is a cross-sectional view of an angled attachment of thetool system of this invention;

[0038]FIG. 23 is an enlarged cross-sectional view of the attachment ofFIG. 22;

[0039]FIG. 24 is a cross-sectional view of the intermediate drive shaftof the attachment of FIG. 22;

[0040]FIG. 25 is a perspective view of the push rod of the attachment ofFIG. 22;

[0041]FIG. 26 is a perspective view of the alignment sleeve of theattachment of FIG. 22;

[0042]FIG. 27 is a perspective view of another attachment of thisinvention;

[0043]FIG. 28 is a cross-sectional view of the attachment of FIG. 27;

[0044]FIG. 29 is an enlarged cross-sectional view of the attachment ofFIG. 29;

[0045]FIGS. 30A and 30B are, respectively, perspective andcross-sectional views of the input drive shaft of the attachment of FIG.27;

[0046]FIG. 31 is an exploded view depicting the arrangement of theoutput drive shaft of the attachment of FIG. 27, and the collet andcollet sleeve that are fitted around the drive shaft;

[0047]FIG. 31A is a cross sectional view of the output drive shaft ofthe attachment of FIG. 27;

[0048]FIG. 32 is a perspective view of the push rod of the attachment ofFIG. 27;

[0049]FIG. 33 is a perspective view of the pusher ring of the attachmentof FIG. 27;

[0050]FIG. 34 is a perspective view of the actuator of the attachment ofFIG. 27;

[0051]FIG. 35 is a perspective view illustrating how the pusher ring ofFIG. 33 and the actuator of FIG. 34 mate.

[0052]FIG. 36 is a perspective view of the proximal end of analternative shaft of the cutting accessory of this invention;

[0053]FIG. 37 is a plan view of the shaft of FIG. 36 wherein the faceson one side of the shaft are seen in plan view;

[0054]FIG. 38 is a plan view of the shaft of FIG. 36 wherein one theside surface of the shaft between the diametrically opposed surfacesthat form face surfaces is seen in plan view;

[0055]FIG. 39 is a cross sectional view taken along line 39-39 of FIG.37;

[0056]FIG. 40 is a side view depicting how a collet holds the shaft ofFIG. 36 to a surgical handpiece;

[0057]FIG. 41 is a side view illustrating how, due to manufacturingtolerances a cutting accessory can possible be bind the feet of thecollet employed to hold the accessory in place. In this Figure, theoffset in alignment of the retention features is exaggerated forpurposes of illustration;

[0058]FIG. 42 is a side view depicting how the shaft of FIG. 36 engagesaligns with the feet of the complementary collet so as to avoid thebinding illustrated in FIG. 41; and

[0059]FIG. 43 is a multi-section cross sectional view of an alternativeattachment of this invention; and'

[0060]FIG. 44 is an exploded view of the attachment of FIG. 43;

[0061]FIG. 45 is a perspective view of the drive shaft internal to theattachment of FIG. 43;

[0062]FIG. 46 is a cross sectional view of the drive shaft of FIG. 45;

[0063]FIG. 47 is a perspective view of the collet internal to theattachment of FIG. 43;

[0064]FIG. 48 is a perspective view of the collet sleeve internal to theattachment of FIG. 43;

[0065]FIG. 49 is a multi-section cross sectional view of an alternativeangled attachment;

[0066]FIG. 50 is an exploded view of the attachment of FIG. 49;

[0067]FIG. 51 is a plan view of the transfer gear internal to theattachment of FIG. 49;

[0068]FIG. 52 is a multi-section cross sectional view of an alternativestraight long attachment of this invention;

[0069]FIG. 53 is an exploded view of the attachment of FIG. 52;

[0070]FIG. 54 is a perspective view of the drive shaft internal to FIG.52;

[0071]FIG. 55 is a cross sectional view of the drive shaft of FIG. 54;

[0072]FIG. 56 is a plan view of the push rod internal to the attachmentof FIG. 52;

[0073]FIG. 57 is a cross sectional view of the push rod of FIG. 56;

[0074]FIG. 58 is a perspective view of the output drive shaft of theattachment of FIG. 52;

[0075]FIG. 59 is a cross sectional view of the drive shaft of FIG. 58;

[0076]FIG. 60 is a cross sectional view of the collet internal to theattachment of FIG. 52;

[0077]FIG. 61 is a cross sectional view of the collet sleeve internal tothe attachment of FIG. 52;

[0078]FIG. 62 is a multi-section cross sectional view of an alternativelong attachment of this invention; and

[0079]FIG. 63 is an exploded view of the attachment of FIG. 62.

DETAILED DESCRIPTION

[0080]FIGS. 1 and 2 illustrate the basic components of the surgical toolsystem 30 of this invention. The system 30 includes a handpiece 32 inwhich a motor 34 (shown in phantom) is housed. An attachment 36 isremovably fitted to the front, distal end of the handpiece. A couplingassembly 38 is disposed inside the attachment 36. Coupling assembly 38releasably holds a cutting accessory 40 to the rest of the system 30.The coupling assembly 38 also transfers the rotational power developedby the handpiece motor 34 to the cutting accessory 40. One suitablehandpiece 32 that can be employed as the handpiece of this system isdescribed in the Applicant's U.S. Pat. No. 5,888,200, which isincorporated herein by reference. This handpiece 32 has two couplingassemblies. A first one of the handpiece coupling assemblies releasablycouples a drive shaft to the rotor of motor 34 so that the drive shaftwill rotate in unison with the motor rotor. A second handpiece couplingassembly integral with handpiece 32 releasably couples the attachment 36over the proximal end of the handpiece. This second handpiece couplingassembly consists of spring feet that engage over feet that areintegrally formed with and extend inwardly from the base of theattachment. A detailed description and illustrations of the couplingassemblies integral with the handpiece 32 are contained in U.S. Pat. No.5,888,200.

[0081] The cutting accessory 40 includes a head 42. The head 42 is theportion of the cutting accessory 40 that is applied to the surgicalsite. A shaft 44 is formed integrally with the head 42 and extendsrearwardly from the base of the head. The attachment coupling assembly38 is releasably locked onto the cutting accessory shaft 44 to transferthe rotational power developed by the handpiece motor 34 to the cuttingaccessory 40. Coupling assembly 38 and shaft 44 are also collectivelydesigned so that the extent to which the shaft extends forward of thecoupling assembly can be selectively set. This selectively allows thesurgeon to regulate the extent to which the cutting accessory head 42extends forward of the handpiece 32.

[0082] Throughout this application, it should now be understood that“forward”, “front” and “distal” shall mean in a direction towards thehead 42 of a cutting accessory 40. “Rearward”, “rear” and “proximal”shall mean in a direction towards the end of the handpiece 32 furthestfrom the accessory head 42.

[0083] A detailed understanding of the structure of the attachment 36and coupling assembly 38 is obtained by initial reference to FIGS. 2 and3. The attachment 36 includes a housing 48 that forms the outer body ofthe attachment. Attachment housing 48 has a front end 50 that has anelongated tube shape. Located rearwardly of the front end 50 attachmenthousing 48 has an intermediate section 52. Intermediate section 52 isthe portion of the attachment housing 48 in which the coupling assembly38 is seated. A collar 54 is rotatably fitted around the intermediatesection 48. The collar 54 is manually displaced to move the couplingassembly 38 between the run state in which the assembly is locked ontothe cutting accessory 40 and the load state in which the cuttingaccessory 40 can be removed from or installed into the attachment 36.Also when the coupling assembly 38 is in the load state, thelongitudinal position of the cutting accessory 40 can be selectivelyset. Attachment housing 48 has a base section 56 located rearward ofintermediate section 52. Base section 56 is generally in the shape of anopen ended tube. A ring-shaped retainer 58 is fitted around the outsideof the open end of the base section 56. Retainer 58 is the portion ofthe attachment 36 that carries the teeth against which the secondcoupling assembly integral with the handpiece 32 engages. Amulti-section bore 59 extends axially through housing 48.

[0084] As seen in FIGS. 3, 4A and 4B, an input drive shaft 60 isrotatably fitted in housing bore 59. The input drive shaft 60 has acylindrically shaped main section 62. A hex-shaped stem section 64extends rearwardly from main section 62. The input drive shaft 60 isfurther formed to have a lip 66 that extends radially outwardly andcircumferentially around the front end of main section 62. An axiallyextending bore 68 extends from the front end of the input drive shaft 60through the main section 62 a distance slightly less than one-half thelength of the main section. Input drive shaft 60 is located in the rearhalf of the housing intermediate section 52 and extends through basesection 56. A bearing assembly 70 which extends between the outside ofshaft main section 62 and an adjacent inner circumferential wall ofhousing intermediate section 52 rotatably couples input drive shaft 60to attachment housing 48. The rearward directed face of shaft lip 66rests against an inner race of the bearing assembly 70, (bearingassembly races not identified). A bearing retainer 72 is threadedlysecured into the attachment housing 48 around the outside of shaft mainsection 62 immediately behind the bearing assembly 70. Bearing retainer72 prevents longitudinal movement of the input drive shaft 60. The stemsection 64 of the input drive shaft 60, it should be understood, isshaped to be locked into the first coupling assembly internal to thehandpiece 32. Thus, the engagement of these two components is whattransfers the rotational power developed by the handpiece motor 34 tothe input drive shaft 60.

[0085] An output drive shaft 76, now described by reference to FIGS. 3,5A and 5B, is securely fitted to input drive shaft 60. Output driveshaft 76 is formed out of a single piece of metal that is shaped to havea cylindrical, solid stem section 78. The stem section 78 of the outputdrive shaft 76 is press fit into the bore 68 of the input drive shaft 60so that the two drive shafts 60 and 76 rotate in unison. Output driveshaft 76 is further formed to have a transition section 80 and a mainsection 82 both of which are located forward of stem section 78.Transition section 80 is located between stem section 78 and mainsection 82. Both transition section 80 and main section 82 are formed tohave circular cross-sectional profiles. The output drive shaft 76 isformed so that main transition section 80 has a diameter greater thanthat of the adjacent stem section 78; main section 82 has a diametergreater than that of transition section 80. A cylindrically shaped headsection 84 extends forward from the front, distal end of shaft mainsection 82. Head section 84 has a diameter less than that of the mainsection 82.

[0086] Output drive shaft 76 is formed with an axially extending bore 86that extends rearward from the front end of bead section 84. Bore 86extends completely through head section 84 and more than half waythrough main section 82. The bore 86 is the space internal to thecoupling assembly 38 in which the proximal, rear end of the cuttingaccessory shaft 44 is fitted. The output drive shaft 76 is furthershaped to have two diametrically opposed, longitudinally extending slots88. Each slot 88 is formed in both the outer surface of the transitionsection 80 and the adjacent surface of the main section 82. Slots 88overlap the rear section of bore 86 but are not in communication withthe bore. The output drive shaft 76 is further formed with a throughchannel 89 that extends diametrically through the bore main section 82.Channel 89 is contiguous with the front ends of slots 88 and extendsthrough bore 86. Channel 89 has generally a rectangular cross-sectionalprofile. The width of channel 89 is less than the width of the adjacentslots 88 for a reason that will be explained hereinafter. In someversions of the invention, this difference in width is approximately0.010 inches.

[0087]FIGS. 3 and 6 illustrate how a collet 90 and a collet sleeve 92cooperate to releasably lock the proximal end of the cutting accessory40 into the output drive shaft 76. The collet 90 is fitted over theoutput drive shaft 76. The collet 90 is formed out of a single piece ofmetal such as flexible stainless steel. Collet 90 is shaped to have aring-shaped base section 93. Two diametrically opposed legs 94 extendforward from base section 93. A foot 96 extends perpendicularly inwardlyfrom the end of each leg 94. The feet 96 are formed to have opposedgripping surfaces 98 that are parallel with the longitudinal axis of thecollet. Each foot 96 is formed to have a bottom surface 102 that isperpendicular to the longitudinal axis of the collet 90.

[0088] Collet 90 is further formed so that a multi-surfaced heel 106 islocated at the end of each leg 94. Each heel 106 is shaped to have atransition surface 108 that angles outwardly away from the outer surfaceof the adjacent leg 94. A butt surface 110 that is parallel with andspaced outwardly away from the adjacent leg 94 forms the bottom of eachheel 106. Thus, heels 106 provide thickness and structure strength tothe adjacent collet feet 96. The illustrated collet 90 is shown to havesemi-circular cuts that extends inwardly from the inner surfaces of thelegs 94 adjacent the feet 96, (cuts not identified). These cuts areformed as a consequence of the manufacture of the collet 90 and do notform any functional part of the invention.

[0089] Collet 90 is fitted over the output drive shaft 76 so that thebase section extends closely around the shaft transition section 80.Collet legs 94 seat in shaft slots 88. The collet feet 96 fit in throughchannel 89 and extend into shaft bore 86. Collectively, the collet 90and shaft 96 are shaped so that collet legs 94 fit loosely in the slots88 and collet feet 96 fit relatively tightly in the through bore 89. Theloose fit of the collet legs 94 in slots 88 facilitates the seating ofthe feet in the slots. As will be discussed more hereinafter, the colletfeet 96 engage the proximal end of the cutting accessory shaft 44 tohold the cutting accessory 40 to the output drive shaft 76.

[0090] As seen in FIG. 6, the collet sleeve 92 has a generallytube-shaped body 114. The collet sleeve 92 is further formed to have anoutwardly extending flange 118 that extends circumferentially around therear, distal end of the body 114. Collet sleeve 92 has an annular edgesurface 116 that is an interface between the ring-shaped front face ofthe sleeve and its cylindrical inner wall. The collet sleeve 92surrounds both collet 90 and output drive shaft 76. Normally, when thecoupling assembly 38 is in the run state, the collet sleeve 92 ispositioned so that the collet heel transition surfaces 108 abut the edgesurface 116 of the sleeve. As seen in FIG. 12A, as a result of thisalignment of the components, there is a small gap 117 between the outersurface of the collet legs 94 and the adjacent inner wall of the colletsleeve 92. As a result of the dimensioning of the components, the colletsleeve 92 urges the collet feet 96 into and holds the feet in the outerdrive shaft bore 86.

[0091] An actuator 120, now described by reference to FIGS. 6 and 7,selectively displaces the collet sleeve 92 rearwardly. Actuator 120 is agenerally ring-shaped member. The front end of the actuator 118 isshaped to have an inwardly directed circumferentially extending lip 122.As seen in FIG. 3, the actuator 120 is fitted over collet sleeve 92 sothat the front end of the actuator, including lip 122, is locatedimmediately forward of sleeve flange 118.

[0092] An understanding of how the actuator 120 is itself displaced isobtained by reference to FIGS. 3, 7, 8 and 8A. As seen in these figures,the actuator 120 is fitted in the attachment housing 48 so as to beclosely located to the inner wall of housing intermediate section 52.This portion of the housing intermediate section 52 is formed with twoopposed slots 124. A ball bearing 126 sits in each slot 124 and extendsbeyond the opposed outer and inner walls of the adjacent section 52 ofthe attachment housing 48. The portion of each ball bearing 126 thatprojects inwardly of the inner wall of the attachment housing 48 seatsin an indentation 128 formed in the outer circumferential wall of theactuator 120. Indentations 128, it will be noted, are opposite eachother and have a cross-sectional profile equal to that of a slicethrough a cone. (In FIG. 7 the pilot holes formed in the actuator 120 toform indentations 128 are illustrated.)

[0093] Collar 54, seen best in FIG. 8B, extends over the portion ofhousing intermediate section 52 in which slots 124 are formed. The innerwall of the collar 54 is formed to have two diametrically opposedgrooves 132, (one shown in phantom). Grooves 132 have an arcuatecross-sectional profile and extend longitudinally along the length ofthe inner wall of collar 54. When the collar 54 is fitted over theattachment housing 48, the outer exposed sections of ball bearings 126each seat in a separate one of the grooves 132. Collar 54 is dimensionedso that it is able to rotate around the attachment housing 48.

[0094] From FIG. 8A it can be seen that each slot 124 is formed to havea generally helically shaped profile. Each slot 124 is further formed tohave a tail section 134 that extends upwardly diagonally away from theproximal end of the slot.

[0095] Returning to FIGS. 2 and 3, it can be observed that a nut 138 isthreaded over the forward end of the housing intermediate section 52.The base of nut 138 has an outwardly directed lip 140. Lip 140 extendsover the forward end of collar 54 to hold the collar to the attachment38. A first spring 142 is located around the output drive shaft 76. Moreparticularly spring 142 extends between the forward-directed face ofinner drive shaft lip 66 and the rearwardly directed face of flange 118of the collet sleeve 92. A second spring 144 is located around the firstspring 142. Spring 144 extends between the static outer race of bearingassembly 70 and the aligned, rearwardly directed end surface of actuator120.

[0096] Inside the front section 50 of the housing it will be observedthat there are three bearing assemblies 142. A first one of the bearingassemblies is fitted around the outer drive shaft head section 84. Thisbearing assembly 143 provides a rotating fit between the outer driveshaft 76 and the inner wall of housing front section 50. A firsttube-shaped spacer 144 separates the second bearing assembly 142described bearing assembly 143. A second spacer 147 separates the secondbearing assembly from the third, and most forward located, bearingassembly 143. A nose cap 146 is press fitted or welded into the open endof the front section 50 of attachment housing 48. Nose cap 146 is formedwith an axially extending through bore, (not identified) through whichthe cutting accessory shaft 44 is inserted into the attachment 36.

[0097]FIGS. 9, 10 and 11 illustrate the shaft 44 of the cuttingaccessory 40. The shaft is formed with a cylindrically shaped main body152 that extends rearwardly from attachment head 42. In some preferredversions of the invention attachment head 42 and shaft 44 are formed outof a single piece of tool steel. Main body 152 has a constantcross-sectional diameter. In some versions of the invention, thediameter of the main body 152 is between 0.032 and 0.500 inches. Instill more preferred versions of the invention, the diameter of the mainbody 152 is between 0.062 and 0.125 inches. Accessory shaft 44 isfurther formed to have a stem 154 that is formed integrally with themain body 152 and that extends coaxially rearwardly from the main body.Stem 154 is generally cylindrical and has an outer diameter that is lessthan the outer diameter of the adjacent shaft main body 152. In someversions of the invention, the diameter of the stem 154 is between 0.010and 0.375 inches. In still more preferred versions of the invention, thediameter of the stem 154 is between 0.032 and 0.093 inches.

[0098] Shaft stem 154 is further formed to define a plurality oflongitudinally spaced apart retention features 156. In the depictedversion of the invention, each retention feature 156 consists of 4planar faces 158 that are formed in the stem and located inwardly of theouter circumferential surface of the stem. The adjacent faces 158intersect at 90° angles. Thus, the faces 158 collectively provide themain portion of the retention feature that they form with a squarecross-sectional profile. It will further be observed that, in theillustrated version of the invention, each retention feature 156 haslower and upper beveled surfaces 160 and 162, respectively, that extendbetween each face and the adjacent portions of the outer circumferentialsurface of the shaft stem 154.

[0099] The cutting accessory 40 of this invention is coated with ananti-corrosive, sterilizable, medically innocuous material, representedby stippling 164 in FIG. 10. Some potential materials that can beapplied to the cutting accessory are: titanium nitride; titaniumaluminum nitride; and titanium carbonitride. The above coatings areavailable from BryCoat Inc. of Safety Harbor, Fla. An alternativetitanium nitride coating that may be suitable is sold as ION-BOND®coating 7-22 by Multi-Arc Inc. of Rockaway, N.J., United States. Anotherpotentially suitable coating is a chromium nitride coating sold asION-BOND® coating 7-24 by Multi-Arc. Another potentially suitablecoating is a zirconium nitride coating sold as ION-BOND® coating 7-40 byMulti-Arc. Silicon nitride may also be a suitable coating. It isbelieved is used, it should be applied to the cutting accessoryaccording to the SILCOSTEEL® process employed by the Restek Corp. ofBellefonte, Pa., United States.

[0100] This material is applied to the cutting accessory 40 so as tohave a maximum thickness of 0.0001 inches. The material covers the wholeof the cutting accessory 40, all of the head 42 and the shaft 44. Inalternative embodiments of the invention, the coating is applied only tothe shaft 44, not to the head 42.

[0101] Attachment 36 is coupled to the handpiece in the same manner inwhich conventional attachments are so fixed. The spring feet of thehandpiece second coupling assembly engage the retainer 58 to releasablysecure the attachment 36 to the handpiece 32. The handpiece firstcoupling assembly releasably locks around the stem section 64 of inputdrive shaft 60. Consequently, the input drive shaft 60 is locked to themotor rotor to rotate in unison with the rotor.

[0102] When a cutting accessory 40 is fitted to attachment couplingassembly 38, accessory stem 154 is at least partially seated in theouter drive shaft bore 86. More particularly, the accessory stem 54 isaligned in the bore 86 so that the diametrically opposed faces 158 ofone of the retention features 156 are aligned with the opposed grippingsurfaces 98 of collet feet 96. When the coupling assembly 58 is in thenormal state, the run state, spring 142 exerts sufficient force oncollet sleeve 92 to push the head, distal end of the sleeve forward.Consequently, the sleeve edge surface 116 is forced against thetransition surfaces 108 of the collet heels 106. This action of thesleeve bearing against the collet heels 106 forces the collet feetinwardly. Consequently, the collet gripping surfaces 98 are forcedagainst the adjacent faces 158 of the cutting accessory retentionfeature 156. Since the collet legs 94 and feet 96 are seated in theoutput drive shaft slots 88 and through bore 89, the collet rotates withthe rotation of the output drive shaft 76. Thus, owing to the engagementof the cutting accessory shaft 44 by the collet 90, the cuttingaccessory 40 likewise rotates in unison with the output drive shaft. Itis through arrangement that the rotational power developed by thehandpiece motor 34 is transferred to the cutting accessory 40. Moreover,since the collet feet 96 fit relatively tightly in the through bore 89,there is little slippage of the feet 96 when they bear against the shaftretention feature 156. Owing to the collet feet 96 bearing against thefaces 158 of the cutting accessory retention features 156, the forwardthrust the surgeon applies to the handpiece 32/attachment 34 istransferred through the coupling assemble to the attachment 40 and, moreparticularly, the attachment head 44.

[0103] It should also be understood that when the handpiece is actuated,the pressing of the accessory head 42 against the surgical site resultsin some rotation of the accessory shaft 44 relative to the output driveshaft 76. The retention feature faces 158 will rotate relative to theadjacent collet feet gripping surfaces 98 that are pressed against thefaces 158. This rotation results in the retention features 156 pushingthe collet feet 96 and heels 106 radially outwardly as depicted by arrow160 in FIG. 12A. The outward movement of the collet feet 96 and heels106 displaces the adjacent collet sleeve 92 rearwardly as represented byarrow 161.

[0104] Eventually, as seen in FIG. 12B, the sleeve 92 is forcedrearwardly to the level at which the inner surface of the sleeve willabut the outer surface of the collet legs 94. Once the collet 90 andsleeve 92 are so aligned, the lever action the collet legs 94 and heels106 can impose against the collet sleeve drops to zero. Consequenatly,when the components of the coupling assembly 38 are so aligned, theoutward movement of the collet legs 94 and feet 96 cannot overcome theforce of spring 142 that holds the collet sleeve 92 in position. Sincethe collet sleeve 92 is itself held in position, the sleeve blocks thefurther outward displacement of the collet legs 94 and feet 96 whichcould result in the release of the cutting accessory 40 from thecoupling assembly 38.

[0105] When the cutting accessory 40 is so coupled to the attachment 36,the two forwardmost bearing assemblies 143 provide a low frictioninterface between the accessory shaft main body 152 and the tubularfront end 50 of the attachment.

[0106] It will also be understood that spring 144 works against thecoupling actuator 120 to urge the actuator in the forward direction.Consequently, when the coupling assembly 38 is in the run state, theactuator 120 is spaced away from the coupling sleeve 92 so as to notlongitudinally displace the coupling sleeve.

[0107] The coupling assembly is transitioned from the run state to theaccessory load state by the rotation of collar 54. Prior to the rotationof the collar, the ball bearings 126 are positioned in the most forwardend of the associated slots 124. The rotation of the collar 54 causesthe ball bearings 126 to be displaced in the slots 124. Moreparticularly, the ball bearings 126 undergo a rearwardly directedhelical movement identical to the profile of the slots 124. Since theball bearings 126 are fitted to actuator 120, the rearward displacementof the bearings results in a like displacement of the actuator. As aresult of the rearward displacement of the actuator 120, actuator lip122 eventually abuts the circumferential flange 118 of the collet sleeve92. As the collar 54 continues its rotation, the actuator 120 continuesto move rearwardly. This rearward movement of the actuator 120 thusforces the collet sleeve 92 to engage in a like path of travel. Therearward translation of the collet sleeve 92 results in the movement ofthe sleeve away from the collet feet 96 and the adjacent section of legs94. Thus, the collet feet 96 are free to be flexed out of outer driveshaft bore 86. When the coupling assembly 38 is in this position, theassembly is considered to be in the accessory load state.

[0108] The continued rotation of the collar 54 causes the ball bearingsto travel into the tail sections 134 of slots 124. When the couplingassembly 38 is in this state, the actuator 120 is still positioned tohold the collar sleeve 92 so that the collet feet 96 are free to flexout of the outer drive shaft bore 86. Also, when the coupling assembly38 is in this state, spring 144 continues to urge the actuator 120 inthe forward direction. When the coupling assembly 38 is in this state,it should be further understood that the collet sleeve flange 118continues to abut actuator lip 122. Spring 142, it will be recalled,continually urges the collet sleeve 92 forwardly. Thus, the force spring142 exerts on the collet sleeve 92 is imposed on the actuator 120. Thus,the forces generated by springs 142 and 144 collectively urge actuator120 forward so that the ball bearings 126 lock in the upper ends of theslot tails 134. Thus, when the coupling assembly 38 is so set, theassembly is locked in the accessory load state.

[0109] When the coupling assembly 38 is in the load state, the accessoryshaft stem 154 can be extended out of or pushed further into the outerdrive shaft bore 86. Thus, the extent to which the accessory shaft 44extends out of the front of the attachment 36 can be selectively set.Specifically, it can be set to a position in which the faces 158 of oneof the shaft's retention features 156 is in registration with the colletgripping surfaces 98. Also, the cutting accessory 40 can be completelyremoved from the attachment 38 and a new accessory fitted to, loadedinto, the attachment.

[0110] When the coupling assembly 38 is in the load state, the colletfeet 96 may still extend a small distance into the outer drive shaftbore 86. During the extension and retraction of the cutting accessory40, the feet will abut against the outer surface of the shaft stem 154.However, since the shaft is formed with flat, beveled surfaces, the feet96 do not lock on planar surfaces formed on the outer surface of theshaft stem 154. Instead the feet ride along the beveled surface to allowthe cutting accessory 40 to be fitted into and removed from theattachment 38.

[0111] Once a cutting accessory is properly fitted into the attachment38, collar 54 is manually rotated to return coupling assembly 38 back tothe run state. As a consequence of this movement of the collar 54, ballbearings 126 travel out of the tail sections 134 of the slots 124 andinto the main sections of the slots. This displacement of the ballbearings 126 allows spring 144 to force the actuator 120 back to itsfully forward position. The return of the actuator 120 to the fullyforward position releases the blocking force the actuator placed on thecollet sleeve 92. Spring 142, in turn, then forces the collet sleeve 92forward so that the sleeve edge surface 116 abuts the collet heeltransition surfaces 108. This action thus returns the collet and therest of the coupling assembly 38 to the run state. It will be notedthat, when the coupling assembly 38 is in the run state with a cuttingaccessory 40 in place, the distance between the butt surfaces 110 of thecollet heels 106 is greater than the inner diameter of the forward endof the collet sleeve 92. Thus, the collet heels 106 prevent colletsleeve from riding up over the forward end of the collet 90.

[0112] The coupling assembly 38 and complementary accessory shaft 44 ofthe tool system 30 of this invention do more than simply allow differentaccessories to be used with a single handpiece 32. Coupling assembly 38and accessory shaft 44 are designed so that the extent to which theaccessory head 42 extends forward from the handpiece 32 can beselectively set. This feature eliminates the need to provide a number ofdifferent accessories that have the same type of head 42 and that differonly in the length of their shafts 44.

[0113] Still another feature of system 30 of this invention, is that thecoupling assembly 38 can be locked in the accessory load state. Thus,when changing cutting accessories 40 or adjusting the extent to which anaccessory extends forward from the handpiece 32, medical personnel donot need to apply force to hold the coupling assembly 38 in the loadstate. The ability to avoid having to perform this task simultaneouslywith the removal, insertion or adjustment of the cutting accessory 40facilitates the quick execution of these latter tasks.

[0114] Still another feature of the system 30 of this invention is thatthe accessory shaft 44 is formed from two sections of differingdiameter. The wide diameter main section 152 provides the shaft 152 withstructural strength. Also, the shaft main section 152 is designed to fitwith bearing assemblies 142 that have inner races that have a relativelywide inner diameter. These bearing assemblies 142 are more economical toprovide than assemblies with narrower inner diameters. The narrowdiameter stem section 154 of the accessory shaft 44 is dimensioned,however, to fit in a relatively narrow diameter outer drive shaft bore86. Since the bore 86 is of narrow diameter the outer drive shaft aswell as the surrounding components can be likewise shaped to have arelatively narrow overall width. The benefit of this feature of theinvention will be discussed in more detail in regard to thebelow-described additional attachments of this invention.

[0115] The cutting accessories 40 of the system 30 of this invention arecovered in a protective coating. If an accessory is not used, it may beexposed to autoclave sterilization; the coating will prevent the toolsteel from which the accessory 40 is formed from discoloring. Thus, eventhough an accessory of this invention is taken out of its sterilepackage, the accessory can be sterilized so that it will be availablefor use in a later procedure. If the accessory is so sterilized, theprotective coating does not discolor. Thus, after autoclavesterilization, the accessory of this invention does not have anaesthetically displeasing appearance that would make surgical personnelreluctant to use the tool.

[0116] An alternative attachment 170 of the system 30 of this inventionis illustrated in FIG. 13. Attachment 170 has an extend-length head tube172. This attachment 170 is used to position the head 42 of a cuttingaccessory 40 at locations that cannot be reached when the accessory isfitted to attachment 36. A detailed understanding of the componentsinternal to attachment 170 is obtained by initial reference to FIGS. 14and 15. Attachment 170 includes a housing 174 that forms the body of theattachment. Head tube 172 is attached to the front of the housing 174. Acoupling assembly 176 is located in the head tube 172 for rotatably andreleasably holding the accessory shaft 44 in the head tube. Couplingassembly 176 also transfers the rotational power developed by the rotorintegral with the handpiece motor 34 to the cutting accessory 40. Asdescribed hereinafter, some components of the coupling assembly 176 arelocated in the housing 174.

[0117] The housing 174 has a base 178 similar in shape to the basesection 56 of previously described and illustrated housing 48. Aretainer 58 is fitted around the outside open end of attachment housingbase 178. Located forward of base 178, housing 174 is formed to have aneck 180. Housing 174 is shaped so that neck 180 has a generallyconstant diameter cylindrical outer surface. Base 178 is shaped to havea frusto-conical section 182 located immediately rearward of the neck180 and generally constant diameter cylindrical section 184 that extendsrearwardly from frusto-conical section 184. An axially extendingmulti-section bore 187 extends through the housing from the front of theneck 180 to the rear end of the base 178.

[0118] Head tube 172 is seated in the front end of the housing bore 187and extends forward from the housing 174. The head tube 172 is formed tohave a flange 188 that extends radially outwardly and circumferentiallyaround it rear end. When head tube 172 is seated in housing 178, flange188 abuts the annular front face of housing neck 180 to limit the extentto which the head tube is seated in housing bore 187. A sleeve-like nut190 is threadedly engaged with complementary threading formed on thehousing neck 180 immediately rearward of the front face of the neck,(threading not identified) Nut 190 is formed with a lip 191 that extendsover the forward facing surface of tube flange 188. Nut 190 thus pressesagainst flange 188 to secure head tube 172 to housing 174.

[0119] An input drive shaft 192, now described by reference to FIGS. 15,16A and 16B, is rotatably fitted in housing 174. Input drive shaft 192has a solid cylindrical main body 194. Extending rearwardly from mainbody 194, the input drive shaft 192 has a hex-shaped stem section 196.Stem section 196 of input drive shaft 192 has the same shape andperforms the same function as stem section 64 of previously describedinput drive shaft 60. The input drive shaft 192 is further formed tohave an annular lip 198 that extends radially and circumferentiallyaround the main body 194 a slight distance in front of the front end ofthe main body. Input drive shaft 194 also has a cylindrical neck 202that is coaxial with and extends forward from the main body 194. Theinput drive shaft is formed so that the outer diameter of neck 202 isless than the outer diameter of the adjacent main body 194.

[0120] Input drive shaft 192 is also formed to have a bore 204 thatextends axially rearward from the front end of the neck 202. Bore 204extends through neck 202 and a short distance into the main body 194 ofthe shaft 192. It will be noted that the shaft 192 is formed so that lip198 is located a slight distance rearwardly of the base of bore 204. Theinput drive shaft is further formed with a pair of diametrically opposedslots 208 that are located around bore 204. Slots 208 extend inwardlyfrom the outer surface of shaft main body 194 and are in communicationwith bore 204.

[0121] A bearing assembly 209 rotatably couples input drive shaft 192 inbore 187 of attachment housing 174. Shaft lip 198 abuts the forwarddirected surface of the inner race of the bearing assembly 209, (racesnot illustrated). A bearing retainer 210 is fitted around the portion ofshaft main body 194 located immediately rearward of the bearing assembly209. The bearing retainer 210 is threadedly secured to an adjacent innerwall of the housing 174 that defines bore 187. The bearing retainer 210holds the input drive shaft 192 in position

[0122] Coupling assembly 176 includes an output drive shaft 214, nowdescribed by reference to FIGS. 15, 17 and 18, in which the accessoryshaft stem 154 is releasably secured. The output drive shaft 214 isgenerally cylindrically shaped and is formed to have a tail section 216that has a first outer diameter. A bore 218, depicted in phantom in FIG.17, extends forward from the rear end of the tail section 216 partiallythrough the tail section. Output drive shaft 214 is further formed so asto have a pair of opposed, elongated, oval-shaped grooves 220 in thetail section. Grooves 220 are located around bore 218 and are incommunication with the bore 218. Output drive shaft 214 has a mainsection 222 located forward of tail section 216. Main section 222 has anouter diameter greater than that of the tail section. The output driveshaft 214 also has a neck 224 located forward of main section 222 and ahead 226 located forward of the neck 224. Output drive shaft 214 isformed so that neck 224 has an outer diameter less than that of mainsection 222 and head 226 has an outer diameter less than that of theneck.

[0123] An elongated bore 228 extends axially and rearwardly throughshaft 214 from the front end of head 226. Bore 228 extends through head226 and neck 224 and partially through main section 222. Bore 228 issized and shaped to receive the accessory shaft stem 154. The outputdrive shaft 214 is further formed to have two diametrically opposedslots 230. Slots 230 extend from a forward portion of shaft tail section216, through main section 222 and partially through neck 224. Theforward portions of slots 230 surround the longitudinal section of theshaft 214 in which the tail end of bore 228 is formed. Slots 230,however, do not directly communicate with the bore 228. The output driveshaft 214 is also formed with a through channel 231. The through channel231 is located adjacent the front ends of the slots 230, extendsdiametrically through the shaft 214 and intersects bore 228.

[0124] Bearing assemblies 234 extend around shaft tail 216 and shafthead 226. The bearing assemblies rotatably hold the output drive shaftin the head tube 172.

[0125]FIG. 18 depicts how the output drive shaft 214, a collet 238 and acollet sleeve 240 cooperate to form the forward-located components ofcoupling assembly 176. Collet 238 is formed of the same material, andhas the same general function, as the previously described collet 90.Collet 238 has a ring-shaped base 242. Two diametrically opposed legs244 extend forward from base 242. An inwardly directed foot 246 islocated at the end of each leg 244. Each foot 246 has a gripping surface247. The collet 238 is formed so that gripping surfaces 246 are parallelwith the longitudinal axis of the collet. The collet 238 is furtherformed to have a small heel 248 between the end of each leg 244 and theassociated foot 246. Each heel 248 is shaped to have a first beveledsurface 250 that extends diagonally outwardly and forwardly away fromthe outer surface of the associated leg 238. The heel 248 has a flatsurface 252 that extends forward from the first beveled surface.Collectively, the flat surfaces 252 of the ankles 248 are parallel witheach other. Each ankle 248 also has a second beveled surface 254.Beveled surfaces 254 extend forwardly and inwardly relative to the flatsurfaces 252 with which the beveled surfaces 254 are contiguous. Thebeveled surfaces 254 terminate at the exposed, front-facing ends of thecollet feet 246.

[0126] The collet base 242 is fitted over the tail section 216 of theoutput drive shaft 214. The collet 238 is fitted to the output driveshaft 214 so that collet base 242 is located forward of shaft grooves220. The collet legs 244 are seated in the opposed slots 230 formed inshaft 214. The collet feet extend into the through channel 231 andproject into shaft bore 228.

[0127] Collet sleeve 240 is a generally tube-shaped structure. As seenin FIGS. 18 and 19, coaxial holes 258 are formed in the rear end of thesleeve 240. The collet sleeve 240 is further shaped to havediametrically opposed windows 260 located rearward of the front end ofthe sleeve. Windows 260 are generally rectangular shaped andlongitudinal axes that are parallel with the longitudinal axis of thesleeve 240. The collet sleeve 240 is further formed so that adjacent thefront end of the sleeve, the inner wall has a lip surface 262. Lipsurface 262 has a constant diameter that is less than the diameter ofthe remaining sections of the inner wall of the sleeve 240. A taperedtransition surface 264 extends circumferentially around the sleeve 240adjacent lip surface 262. The diameter of the inner wall of the sleevelocated rearwardly of transition surface 264 is constant.

[0128] Collet sleeve 240 is slip fitted over both output arrive shaft214 and collet 238. When the coupling assembly 176 is in the run state,the collet sleeve 240 is initially positioned so that transition surface264 abuts the second beveled surfaces 254 of the collet 238. When thecoupling assembly is in this state, as seen by FIG. 21A, there is asmall interstitial gap 249 between the collet flat surfaces 252 and theadjacent, constant diameter inner wall of the collet sleeve 240. Owingto the dimensioning of the components, when the collet sleeve 240 is inthis state, the sleeve thus holds the collet feet 246 in the shaft bore228.

[0129] It will further be understood that the collet sleeve 240 isfurther positioned over the collet 238 so that the sleeve windows 260are in registration with the collet legs 244. Also, the holes 258located in the rear end of the collet sleeve 240 are in registrationwith grooves 220 formed in the drive shaft tail section 216.

[0130] A push rod 262, now described by reference to FIGS. 15 and 20,selectively displaces the collet sleeve when the coupling assembly 176is in transition from the run state to the accessory load state. Thepush rod 262 is a generally solid cylindrical member that extends fromthe housing neck 180 into the head tube 172. The most rearwardly locatedsection of the push rod 262 is the tail 263. The tail 263 is formed witha through hole 264 that extends laterally through the tail. Immediatelyforward of tail 263, push rod 262 is formed to have a first intermediatesection 266. The longest section of the push rod 262 in terms of length,is the main section 268 which is located immediately forward of thefirst intermediate section 266. The push rod 262 is shaped so that theouter diameter of the first intermediate section 266 is greater than theouter diameter of the tail 262; the main section 268 has an outerdiameter greater than that of first intermediate section 266. A secondintermediate section 270 extends forward from the front of the mainsection 268. The push rod 262 is further formed to have a head 272 thatextends forward from second intermediate section 270. The push rod 262is further shaped so that the second intermediate section has an outerdiameter less than that of the main section 268. The head 272 of thepush rod has an outer diameter less than that of the adjacent secondintermediate section 270. Push rod 262 is further formed so that athrough hold 274 extends laterally through the center of the head 272.

[0131] The push rod 262 is assembled into attachment 170 so that the rodtail 263 is slideably fitted inside bore 204 of the input drive shaft192. A pin 276 extends through the drive shaft slots 208 and rod throughhold 264. Pin 276 thus connects the push rod 262 to the input driveshaft 192 so that the rod rotates with the shaft. However, pin 276 isdimensioned to be able to slide relative to slots 208. Thus, push rod262 is capable of a limited degree of longitudinal movement relative tothe input drive shaft 192. Pin 276 is dimensioned so that the ends ofthe pin extend beyond the outer surface of the drive shaft neck 202. Theopposed ends of pin 276 are seated around an annular retaining ring 277.Ring 277 is fitted around the outside of drive shaft neck 202. The ring277 is dimensioned so that it is able to move longitudinally relative tothe input drive shaft 192. The retaining ring 277 is provided withdiametrically opposed holes, (holes not identified). When the attachment170 is assembled, the opposed ends of pin 276 are press fit into theholes of the retaining ring 277.

[0132] The head 272 of the push rod 262 is seated in the bore 218 formedin the tail section 216 of the output drive shaft 214. A pin 278 extendsthrough collet sleeve holes 258, outer drive shaft grooves 220 and rodthrough hole 274. Pin 278 thus connects the push rod 262 to the driveshaft 214 so that these two components will rotate in unison and so thatthe rod is able to move longitudinally relative to the drive shaft. Thepin 278 also connects the push rod 262 and the collet sleeve 240together so that these components both rotate together in unison aidengage in the same longitudinal movement.

[0133] An actuator 282 located in the housing neck 180 longitudinallydisplaces the push rod 262. Actuator 282 is similar in shape topreviously described actuator 130. Actuator 282 typically will besmaller in diameter than actuator 120. Actuator 282, it will beobserved, is fitted over the neck 202 of the input drive shaft 192 so asto surround the push rod tail 262 and pin 276. A forward facing lipsurface 284 of the actuator 282 is located in close proximity to theretaining ring 277.

[0134] Housing neck 180 is formed with slots 286 similar to previouslydescribed slots 124 (FIGS. 8 and 8A). A collar 288 essentially identicalto collar 54 is rotatably located over the housing neck 180. Nut 190holds collar 288 onto the housing 174.

[0135] A ball bearing 287 is seated in each slot 286. Each ball bearing287 has one end that is seated in the indentation formed in the actuator(indentation not identified). The opposed end of each bearing is seatedin a groove 292 formed in the collar 288. Slots 286, it should beunderstood, are arranged so that when the coupling assembly 176 is inthe run state, the ball bearings are located in close proximity towardsthe housing base 178. Slots 286 are further shaped so that, as thecollar is rotated to move the coupling assembly to the accessory loadstate, the bearings 126 will be displaced forwardly towards the frontend of the attachment 170.

[0136] Additional bearing assemblies 234 provide low friction, rotatinginterfaces between the components of the moving components of attachment170 and head tube 172. One bearing assembly 234 extends between inputdrive shaft neck 202 and the head tube 172. Two spaced apart bearingassemblies 234 rotatably hold the push rod main section 268 in the headtube. Additional bearing assemblies 234 provide a low friction interfacebetween the attachment shaft main section 152 and the head tube 172.Spacer sleeves 294 slip fit in the head tube 172 hold the bearingassemblies 234 apart from each other.

[0137] A spring 298 extends between the output drive shaft 214 and thepush rod 262. More particularly, spring 298 extends between a firstwasher 299 disposed around push rod 298 that abuts the tail end of thedrive shaft 214 and a second washer 302 seated against a stepped surfaceof the push rod between main section 268 and second intermediate section270. A second spring 306 extends between an inwardly directed annularstep 308 formed in the attachment neck 180 and the actuator 282.Specifically, spring 306 abuts the annular, front facing surface of theactuator 282.

[0138] Normally, spring 298 works against push rod 262 so as to push thepush rod rearward, towards the input drive shaft 192. The push rod 298,in turn, forces the collet sleeve 240 to engage in a similar, rearward,displacement. Consequently, the surface 264 of the sleeve 240 is urgedagainst the second beveled surfaces 254 of the collet ankles 248. Thislatching action serves to hold the collet feet 246 inside output driveshaft bore 248. When a cutting accessory 40 is seated in bore 228, thegripping surfaces 247 of the collet feet 246 thus bear against theadjacent faces 158 of the accessory stem 154 so as to hold the accessoryin the output drive shaft 214. Spring 306, it will be noted, urgesactuator 282 rearward. Consequently, the lip surface of the actuator 282is held away from the retainer ring 277. Thus, the actuator 282 isprevented from unintentionally striking the retaining ring 277 whichwould cause the inadvertent longitudinal displacement of the push rod298 and collet sleeve 240.

[0139] When the attachment 170 of this version of the invention iscoupled to the handpiece 32, input drive shaft 192 is rotatably coupledto the rotor integral with the handpiece motor 34. The push rod 298transfers the rotational movement of the input drive shaft 192 to boththe output drive shaft 214 and collet sleeve 240. Owing to the seatingof the collet legs 244 in the slots 230 and the seating of the colletfeet 246 in the through channel 231, the collet 238 is forced into alikewise rotational motion. Thus, when a cutting attachment 40 is lockedinto the output drive shaft 214, it undergoes the same rotational motionexperienced by the drive shaft 214.

[0140] When the cutting accessory 40 is pressed against the surgicalsite, there may be some rotation of the accessory shaft 44 relative tooutput drive shaft 214. When this occurs, the collet feet 246 may bepushed radially outwardly against the collet sleeve 240 as representedby arrow 311 of FIG. 21A. Owing to the relationship collet surface 254to collet sleeve surface 264, the movement of the collet feet 246results in the forward displacement of the collet sleeve 240,represented by arrow 312. The displacement of the collet sleeve 240results in the constant diameter section of the inner wall of the sleeveadjacent surface 264 from going into registration with and abutting theflat surfaces of the collet 238 as seen in FIG. 21B. Once the componentsof the coupling assembly 176 are so aligned, the lever angle againstwhich the collet feet 246 are pushing falls to zero. Thus, when thecollet 238 and the sleeve 240 are in this orientation, the collet feet246 are no longer able to exert a force on the sleeve that will resultin the displacement of the sleeve to the accessory load state.

[0141] The coupling assembly 176 of this version of the invention isdisplaced from the run state to the accessory load state by the manualrotation of collar 288. The rotation of the collar 288 causes the ballbearings 126 to move in a generally forward direction in the slots 286in which the ball bearings are seated. The movement of the ball bearings126 forces a like, forward movement of the actuator 282. As a result ofthis forward movement, the actuator 282 strikes the retaining ring 277.As the actuator 282 continues to move forward, it causes the retainingring 277 and therefore also the push rod 262 to engage in a like forwardtranslational motion. The push rod 262, in turn, forces the colletsleeve 240 to move in the same general direction. As a result of thedisplacement of the collet sleeve 240, the sleeve windows 260 aredisplaced to the point at which they come into registration over theends of the collet legs 244 and the feet 246. When the collet sleeve 240is so positioned, the legs 244 and feet 246 are free to flex out of thedrive shaft bore 228. Since the collet feet are not locked against oneof the stem retention features 156, the accessory stem 154 can beremoved from, inserted into or repositioned in the output drive shaft214.

[0142] Attachment 170 of the system 30 of this invention is used when itis necessary to position the head 42 of the cutting accessory 44 moreforward of the handpiece 32 than it can be positioned when usingattachment 36. It will be noted that, while a portion of the attachmentcoupling assembly 176 is located in head tube 172, the mechanism thattakes the assembly 176 in and out of the run state is mounted to thehousing 174. This arrangement makes it possible to keep the diameter ofthe head tube relatively small. For example, in some preferred versionsof the invention, the outer diameter of the head tube 172 is 0.313inches or less, in more preferred versions of the invention, the outerdiameter of the head tube 172 is 0.235 inches or less and, in still morepreferred versions of the invention, the outer diameter of the head tube172 is 0.125 inches or less. An advantage of the head tube 172 havingsuch a small diameter is that it reduces the extent to which the headtube obstructs the surgeon's field-of-view of the surgical site.

[0143] Moreover, in some versions of the invention, the head tube 172may be formed with a tapered profile. An advantage of these versions ofthe invention is that the extent to which the forward end of theattachment 170 obstructs the field-of-view of the surgical site is evenfurther reduced.

[0144] Still another feature of this invention is that it will berecognized that collet 238 is positioned in head tube 172 a selectdistance from the distal end of the head tube. Specifically, thisdistance is such that it is possible for cutting accessory 40, with itssingle-length shaft 44, be held to attachment 36 by collet 90 and alsoheld to attachment 170 by collet 238. Thus cutting accessories havingshafts that have a single, common length can be used with both themedium and long length attachments of this invention.

[0145] An angled attachment 320 of the system 30 of this invention isdepicted in FIGS. 22 and 23. Attachment 320 is used by surgeons thatwant to apply the head 42 of the cutting accessory 40 to the surgicalsite along an axis that is angled from the longitudinal axis of thehandpiece 32. Often a surgeon uses this type of attachment 320 forergonomic reasons or to minimize the extent the handpiece obstructs thefield-of-view of the surgical site.

[0146] Attachment 320 includes a housing 322. This housing may be formedfrom a single piece of metal or from plural workpieces that are securedtogether. Housing 322 is shaped to have a base 324 similar to base 178of attachment 174. Not illustrated is the retaining ring that is fittedover the open end of the base 324. Housing 322 is further formed to havea shoulder 326 and a neck 398 that are located forward from the base324. The shoulder 326 is located immediately forward of the base 324 andis coaxially aligned with the base. Neck 328 extends forward fromshoulder 326 and is angularly offset from the shoulder. A multi-sectionbore 327 extends axially through housing base 324 and shoulder 326. Amulti-section bore 329 extends axially through housing neck 328. Bores327 and 329 are in communication with each other. A head tube 330extends forward from the open end of housing neck 328. A couplingassembly 334 is mounted in the neck 328 and the head tube 330 forreleasably and rotatably holding the cutting accessory 40 in the headtube.

[0147] An input drive shaft 336 is rotatably mounted in housing base322. The input drive shaft 336 includes a stem section 338 similar inshape and identical in function to previously described stem section196. Forward of stem section 338, input drive shaft 336 is formed tohave a cylindrical leg 340. Forward of leg 340, the input drive shaft336 has a cylindrical shoulder section 342. The input drive shaft 336 isformed so that shoulder section 342 is wider in diameter than leg 340.The input drive shaft also has a head 344 that extends forward from andis integrally attached to shoulder section 342. Drive shaft head 344 hasa circular cross-sectional profile and a diameter less than the diameterof the shoulder section 342.

[0148] The stem section 338 and leg 340 of the input drive shaft 336 arelocated in the base 324 of attachment housing 322. The shoulder section342 and head 344 of the shaft are located in the housing shoulder 326.Bearing assemblies 346 and 348 rotatably secure the input drive shaft336 in the attachment housing 322. Bearing assembly 346 is fitted aroundthe portion of shaft leg 340 located adjacent shoulder section 342.Bearing assembly 348 is located against a stepped surface of the shaft336 between shoulder section 342 and head 344.

[0149] As will be discussed below, the drive shaft head 344 is providedwith gear teeth 345.

[0150] An intermediate drive shaft 356 is rotatably secured in the bore329 of housing neck 328. The intermediate drive shaft 356, seen best inFIGS. 23 and 24, is formed to have a large diameter base 358 that islocated adjacent input drive shaft head 344. Base 358 is provided withteeth 359 that engage the gear teeth 345 of head 344. Gear teeth 345 and359 are beveled to facilitate the transfer of rotational power fromshaft 336 to shaft 356 even though the longitudinal axes of the shaftsare angled relative to each other. Forward of base 358, the intermediatedrive shaft 356 has a main body 360 that is cylindrical in shape andthat has an outer diameter less than that of the base. The intermediatedrive shaft 356 is also formed to have a head 362 that extends forwardfrom the base 360. Shaft head 362 is shaped to have a tongue-like shape.That is while the sides of the head 362 have an arcuate profile, the topand bottom surfaces of the head are flat and coplanar.

[0151] In one preferred method of manufacturing the invention, the stemsection 338, leg 340, shoulder section 342 and the rear portion of head344 of the input drive shaft 336 are formed from a single workpiece. Abore, (not identified), is formed in the workpiece so as to extendrearwardly from the shoulder section 342. A second workpiece that couldfunction as an intermediate drive shaft is press fit in the bore. As aresult of this assembly process, the teeth, which would normally be thebase teeth of the intermediate drive shaft, instead function as teeth345 of the input drive shaft 336. An advantage of this method ofmanufacture is that it eliminates the expense of having to form teeth inthe shaft head 344.

[0152] Two bearing assemblies 363 rotatably secure intermediate driveshaft 356 in bore 329. The inner race of the most rearward of the twobearing assemblies 363 is seated against the shoulder between the shaftbase 358 and main body 360. The forward one of the bearing assemblies363 extends around a more forward section of shaft main body 360. Atube-shaped spacer 364 holds the bearing assemblies apart from eachother. The spacer 364 bears against the inner wall of the housing 322that defines bore 329. Two set screws 361 bear against the spacer 364 tohold the spacer in place. Set screws 361 extend through openings in thehousing shoulder 326, (openings not identified).

[0153] As discussed above, the attachment coupling assembly 334 ispartially located in head tube 330. Coupling assembly includes theoutput drive shaft 214, the collet 238 and collet sleeve 240 previouslydescribed with respect to coupling assembly 176. Bearing assemblies 234fitted around shaft tail 216 shaft head 226 provide a low-frictioninterface between the shaft 214 and the adjacent inner wall of head tube330.

[0154] A push rod 366, now described by reference to FIGS. 23 and 25,rotatably connects intermediate drive shaft 356 to the associated outputdrive shaft 214. Push rod 366 is in the form of a solid, cylindricalrod. The push rod 366 is shaped to have a main section 368 that has aconstant outer diameter. The push rod 366 is further formed so as todefine an elongated rectangular slot 370 that extends forward from therear end of main section 368. Extending forward from main section 366,push rod 366 is formed to have a head 372. Head 372 is cylindrical andhas an outer diameter less than that of main section 368. Rod head 372is formed with a hole 374 that extends axially therethrough.

[0155] The push rod 366 is mounted to the attachment 366 so that thehead 362 of the intermediate drive shaft seats in rod slot 370. Rod head372 seats in the bore 218 formed in the tail section 216 of the outputdrive shaft 214. A pin 376 extends through collet sleeve holes 258,outer drive shaft grooves 220 and rod hole 374. A bearing assembly 234that extends between rod main section 368 and the inner wall of headtube 330 rotatably couples the push rod in the head tube. It willfurther be observed that a sleeve 378 extends around the rear end of thepush rod 366.

[0156] An actuator 382 mounted in the housing neck 328 selectively,longitudinally displaces the push rod 366. Actuator 382 has the samegeneral shape as the first-described actuator 130. However, actuator 382is both smaller in diameter and length than actuator 130. Actuator 382is normally positioned around the front end of the main body 360 ofintermediate drive shaft 356. The actuator 382 is oriented so that theend of the actuator with the inwardly directed lip faces the push rod366. Housing neck 328 is formed with opposed slots 384 in which ballbearings are seated. The ends of ball bearings 385 seat in theindentations formed in the actuator 382.

[0157] A collar 386 is rotatably fitted over housing neck 328. Collar386 is similar in shape though smaller in diameter to previouslydescribed collar 288. The sections of the ball bearings 385 that extendout of slots 384 seat in the grooves formed along the inner wall of thecollar 288, (grooves not identified). Normally, coupling assembly 334 isconfigured so that the ball bearings 385 are positioned in the ends ofthe slots 384 located closest to housing shoulder 326.

[0158] Head tube 330 has a base 388 with a diameter greater than that ofthe rest of the tube. Tube base 388 is threadedly secured to the portionof housing neck 328 located forward of collar 386, (threading notillustrated). The head tube base 388 thus holds collar 386 in positionover the housing neck 328. Attachment 320 further includes an alignmentsleeve 390. Sleeve 390, depicted best in FIGS. 23 and 26, has a rear end392 with an outer diameter dimensioned to facilitate the snug securementof the sleeve in the open end of housing neck 328. The sleeve 390 alsohas a front end 394. The outer diameter of sleeve front end 394 isdimensioned so, when the head tube 330 is fitted over the end 394 tosecure the tube to housing 322, the tube tightly fits against the sleeve390. Sleeve 390 is also provided with a lip 396 that extends outwardlyaway from the outer surface of the sleeve. Lip 396 is located betweenthe rear and front ends of the sleeve 392 and 394, respectively. Whenthe sleeve 390 is mated to the housing 322, lip 396 limits the extent towhich the sleeve is inserted in the neck bore 329.

[0159] A spring 398 extends between the rear face of the input driveshaft 214 and push rod 366. More specifically, the rear end of spring398 seats against the annular shoulder of push rod 366 located betweenits main section 368 and the head 372. Spring 398 displaces the push rod366 rearwardly so that push rod holds the collet sleeve 240 against thecollet ankles 248. Thus, spring 398 latches the collet sleeve 240 sothat the sleeve holds the collet feet 246 in the run position. A spring402 extends between the rear end of the alignment sleeve 390 and theadjacent forward-directed face of actuator 382. Spring 402 urgesactuator 382 away from the adjacent ends of push rod 366 and sleeve 378.

[0160] It will further be observed that additional bearing assemblies234 are fitted in the head tube 330 forward of output drive shaft 214.Bearing assemblies 234 provide a rotating interface between theaccessory shaft main body 152 and the adjacent inner wall of the headtube 330. Sleeves 294, 295 and 297 hold the bearing assemblies 234 apartfrom each other. A nose cap 146 is fitted into the open end of the headtube 330.

[0161] Attachment 320 is used in a manner similar to that in whichattachment 170 is used. The rotational movement applied to the inputdrive shaft 336 from the handpiece motor 34 is transferred through theintermediate drive shaft 356 and the push rod 366 to the output driveshaft 214. Owing to the latching of the collet feet 246 in the driveshaft bore 228, the collet 238 transfers the rotational movement of theoutput drive shaft 214 to the cutting accessory 40 against which thefeet abut.

[0162] Coupling assembly 334 of this version of the invention is movedfrom the run state to the accessory load state by the rotation of collar386. The rotation of collar 386 causes ball bearings 385 to be displacedin the forward direction in the housings slots 384. The movement of theball bearings 385 causes a like forward movement of the actuator 382. Asa result of the forward movement, actuator 382 eventually strikes anddisplaces sleeve 378. The forward translation of sleeve 378 causes alike movement of the push rod 366. The displacement of the push rod 366causes the forward movement of the collet sleeve 240 that results in thecoupling assembly being placed in the accessory load position.

[0163] The attachment 320 of the system 30 of this invention provides analternative means for the surgeon to apply the accessory head 42 to asurgical site. Head tube 330 of attachment 320 has the same narrowcross-sectional width of previously described head tube 174.Accordingly, the extent to which head tube 330 obstructs thefield-of-view of the surgical site is minimized. Moreover, the outerdiameter of the housing shoulder and neck sections 326 and 328,respectively, is likewise minimized. Specifically in some preferredversions of the invention the maximum diameter of the housing shoulderand neck sections 326 and 328, respectively, including collar 386, is0.750 inches or less. In more preferred versions of the invention, themaximum diameter of these components is 0.400 inches or less. In stillmore preferred versions of the invention, the maximum diameter of thesecomponents is 0.350 inches or less. An advantage of these componentshaving this relatively narrow diameter is that it means the extent towhich the forward portions of the attachment 320, which contain thecoupling assembly 334, obstruct the field-of-view of the surgical siteis likewise minimized.

[0164] FIGS. 27-29 depict another attachment 410 of the system 30 ofthis invention. Attachment 410 is a medium length attachment that isused to position the cutting accessory 40 in situations in whichattachment 36 is too short and attachment 170 is too long. Attachment410 includes the previously described housing 174. A head tube 172 a,which is a shortened version of head tube 172, extends outwardly fromthe front of housing 174. A coupling assembly 412 is located in the headtube 172 a and housing 174 for rotatably and releasably holding theaccessory shaft 44 in the head tube.

[0165] Attachment 410 has an input drive shaft 412 depicted in FIGS. 30Aand 30B. Drive shaft 414 has the main body 194, the stem section 196 andannular lip 198 of previously described input drive shaft 192. Forwardof annular lip 198, input drive shaft 414 is shaped to have a neck 416that has a diameter less than that of the main body 194. A head 418,which has a diameter less than that of the neck 416, extends forward ofthe neck.

[0166] The input drive shaft 414 is shaped to have a bore 420 thatextends from the front end of the head 418, through the head into thefront of the neck 416. A rectangular-shaped opening 422 extendsdiametrically through the neck 416. The rear end of bore 420 is incommunication with the front end of opening 422. The input drive shaft414 is further formed to have an annular groove 424 that is locatedimmediately behind the front end of neck 416. Specifically, groove 424is located between the front end of neck 416 and slots 422.

[0167] Input drive shaft 414 is rotatably fitted in housing 174 in thesame manner in which drive shaft 192 is fitted in the housing. Shafthead 418 extends into the open rear end of head tube 172 a. A bearingassembly 308 rotatably holds the shaft head 418 in the head tube 172 a.A retention clip 423 holds bearing assembly 308 in position. Theretention clip 423 is seated in the groove 426 formed in the front ofthe shaft neck 416. A small spacer ring 425 is fitted around the shaftneck and head 416 and 418, respectively. Spacer ring 425 holds thebearing assembly 308 away from retention clip 423.

[0168] An output drive shaft 426, now described by reference to FIGS. 31and 31A, is rotatably fitted in head tube 172 a. The output drive shaft426 includes a tail section 428 that has a first diameter. Anintermediate section 430 that has a diameter greater than that of thetail section 428 extends forward from the tail section. The output driveshaft 426 also has a main section 432 that is located forward of theintermediate section 430. Main section 432 has a diameter that isgreater than that of the tail section 430. A head 434, that has adiameter approximately equal to that of the intermediate section 430,extends forward from the main section 432.

[0169] The output drive shaft 426 has a circular bore 436 that extendsforward from the rearwardly directed face of tail section 428. Bore 436extends through the tail section 428 and into intermediate section 430.Output drive shaft 426 also has a rectangularly shaped opening 438 thatis located immediately forward of bore 436. The output drive shaft 426is formed so that opening 438 is located in the intermediate section430. Immediately rearward of opening 438, the output drive shaft 426 soas to have an annular groove 440 that extends circumferentially aroundthe outer surface of the shaft intermediate section 430.

[0170] A bore 442 extends axially rearwardly through the output driveshaft 426 through the head 434 and partially through the main section432. Bore 442 is sized and shaped to receive accessory shaft stem 154.Slots 444 are formed in diametrically opposed sections of the outersurface of the shaft intermediate and stem sections 430 and 432,respectively. Slots 444 are not in communication with bore 442. Athrough channel 446 extends diametrically through the shaft main section432. Through channel 448 is contiguous with the front ends of slots 444and intersects bore 442.

[0171] From FIG. 29 it can be seen how output drive shaft 426 isrotatably held in head tube 172 a. A bearing assembly 308 is fitted overthe shaft head 434 to provide a first rotatable coupling between theshaft 426 and the head tube 172 a. A second bearing assembly 308 isfitted over the shaft tail section 428. The second bearing assembly 308likewise providing a low friction interface between the shaft 426 andthe head tube 172 a so as to allow the shaft to rotate relative to thehead tube. A retention clip 423 is snap fitted in the annularinterstitial space in output drive shaft groove 440. Retention clip 423prevents the bearing assembly 308 disposed around the shaft tail section428 from moving in the forward direction. A spacer ring 425 disposedaround the tail section 428 holds the bearing assembly 308 away from theretention clip 423.

[0172] A collet 238 a and collet sleeve 454 that form part of thecoupling assembly 412 are fitted over the output drive shaft 426. Asseen in FIG. 31, collet 238 a has a base 246, legs 244 and feet 246geometrically similar to the like features of collet 238. Collet 238 ais further formed to have a small ankle 458 between the end of each leg244 and the associated foot 246. Each ankle 453 is shaped to have afirst beveled surface 460 that extends diagonally outwardly andforwardly away from the outer surface of the associated leg 238. Theankle 458 has a flat surface 462 that extends forward from the firstbeveled surface 460. Collectively, the flat surfaces 462 of ankles 458are parallel with each other. Each ankle 458 also has a second beveledsurface 464. Beveled surfaces 464 extend forwardly and inwardly relativeto the flat surfaces 462 with which the second beveled surfaces 464 arecontiguous. The outer surface of each collet foot 246, it will be noted,is aligned with the outer surfaces of the leg 244 with which the foot isassociated.

[0173] Collet sleeve 454 is shaped to have a generally cylindrical body468. Body 468 is formed to define two diametrically opposed generallyrectangularly shaped windows 470. The collet sleeve 454 has twodiametrically opposed legs 472 that extend rearwardly from the rear endof body 468. An inwardly directed foot 474 is located at the end of eachleg 472. Feet 474 are each shaped to have a foot pad 476 that is themost inwardly located portion of the foot. Each foot 474 also has a toe478 that is located rearwardly of the foot pad 476 and extends outwardlyrelative to the adjacent foot pad.

[0174]FIG. 32 illustrates a push rod 480 that is integral with couplingassembly 412. Push rod 480 includes a tail 482. While the tail 482 has agenerally circular cross sectional profile, it has an end section withopposed flat surfaces 481. The tail 482 is further formed so that thereare opposed indentations 484 in the arcuate side surfaces of the tailthat extend between the flat surfaces 481. Extending forward from tail482, the push rod 480 has a main body 486 with a generally cylindricalprofile. The main body 486 has an outer diameter greater than that ofthe tail 482. A flange 488 extends circumferentially and outwardlyaround the interface between the push rod tail 482 and the main body486.

[0175] Extending forward from the front end of main body 486, the pushrod 480 is formed to have a cylindrical neck 490. Neck 490 has an outerdiameter slightly less than that of main body 486. The push rod 480 hasa head 492 that extends forward from neck 490. Head 492 has a generallyrectangular profile and is coaxial with the rod tail 482, main body 486and neck 490. The side surfaces of head 492 are, however, curved andflush with the outer surface of neck 490. Two diametrically opposedindentations 494 are formed in the side surfaces of head 492.

[0176] Push rod 480 is rotatably mounted in head tube 172 a. The endsection of the push rod tail 482 is seated in opening 422 formed in theinput drive shaft 414. More particularly, the input drive shaft 414 andthe push rod 480 are shaped so that tail 482 is not able to rotaterelative to the opening 422 but the tail is able to longitudinally slidein the opening.

[0177] A pusher ring 498, depicted in FIG. 33, is fitted around theoutside of the input drive shaft neck 416. Pusher ring 498 is generallytubularly shaped and is dimensioned so as to be slideable over the driveshaft neck 416. The pusher ring 498 is formed so that on the outersurface of the ring there are two rearwardly directed teeth 502. Eachtooth 502 has a base 504 with a bore 506 that extends inwardly towardsthe center of the pusher ring 498. The rearward-directed end of eachtooth 502 is pointed. Pins 508, seen in FIG. 29, are press fit into thering bores 506. The inner ends of pins 508 seat in indentations 484formed in input drive shaft tail 482. Owing to the abutment of pins 508against tail 482, the push rod 480 and pusher ring 498 engage in likerotational and translating motion.

[0178] An actuator 510, seen in FIG. 34, forces the push ring 498forward so as to cause a like motion in the push rod 480. Actuator 510includes a main body 512 that is generally ring-shaped. The actuator ispositioned so that the main body 512 extends around the portion of theinput drive shaft 410 located forward of lip 198. The outer surface ofactuator main body 512 is formed with indentations 514 in which ballbearings 287 (FIG. 28) are seated. The front annular face of main body512 is formed to have an annular rib 516 that extends forward from themain body. Rib 516 is located between the inner and outer perimeters ofthe main body 512. Two teeth 518 a and 518 b extend forward from rib516. Teeth 518 a and 518 b are diametrically opposed from each other.Both teeth are provided with pointed front faces. While the teeth aregenerally identical in shape, tooth 518 b is, however, longer than tooth518 a.

[0179] As in the previously described versions of the invention, ballbearings 287 seat in slots 286 formed in housing 174. The rotation ofcollar 288 fitted over housing 174 results in the forward and rotationalmovement of the ball bearings 287. The displacement of the ball bearings287 results in the like displacement of the actuator 510.

[0180] Returning to FIG. 29, it can be seen that the push rod head 492is seated in opening 438 of the output drive shaft 426. The body 468 ofcollet sleeve 454 is seated over the collet 238 a. The legs 472 ofsleeve 454 extend rearwardly relative to the collet 238 a. The sleevefeet 474 extend into the opposed ends of opening 438 formed in theoutput drive shaft 426. The foot pads 476 of the sleeve feet 474 seat inthe indentations 494 formed in the push rod head 492. A retention clip423 holds the sleeve feet seated immediately forward of the sleeve tothe push rod 480. The retention clip 423 extends around the sleeve feet474 immediately forward of the associated toes 478.

[0181] Spring 298 extends between the output drive shaft 426 and pushrod 480. More particularly, the spring 298 extends between a washer 299disposed around the push rod 480 that abuts the shaft tail section 428and the forward facing surface of the rod flange 488. Spring 298displaces the push rod 480 rearwardly so that the push rod holds thecollet sleeve 454 in the run state. A spring 306 extends between theinwardly directed annular step 308 formed in the housing 174 and theactuator 510. Spring 306 prevents unintended forward movement of theactuator that could result in the inadvertent transition of the couplingassembly 412 from the run state to the accessory load state.

[0182]FIG. 35 illustrates how the actuator 510 works against the pusherring 498 to force the forward displacement of the pusher ring and pushrod 480. Eventually, as result of the forward and rotationaldisplacement of the actuator 510, rib 516 of the actuator abuts teeth502 of the pusher ring 498. The continued forward displacement of theactuator 510 results in the like motion of the pusher ring 498 and thepush rod 480.

[0183] The forward movement of the push rod 480 causes liketranslational motion of the collet sleeve 454. As a result of theforward movement of the sleeve 454, the windows 470 formed in the sleevecome into registration over the collet feet 246. Thus, when the couplingassembly 412 is in this state, the accessory load state, the feet 246are free to flex out of the output drive shaft bore 442 to allow theinsertion, removal or adjustment of the accessory shaft stem 154 fittedin the bore.

[0184] One advantage of the coupling assembly 412 of this version of theinvention is that the interfaces between the input drive shaft 414 andthe push rod 480, between the push rod and the output drive shaft 426and between the push rod and the collet sleeve 454 are accomplishedwithout the need for providing through holes through the push rod. Thus,this coupling assembly is designed in such a way that the structuralfeatures of the push rod 480 do not appreciably weaken the mechanicalstrength of the push rod.

[0185] Still another feature of coupling assembly 412 is that when theassembly is in the accessory load state, teeth 502 of the pusher ring498 abut teeth 518 a and 518 b of the actuator 510. At this time, itshould be understood, that the actuator 510 is locked in a static state.Owing to the engagement of teeth 450 against teeth 513 a and 518 b, thepusher ring 498, and therefore the push rod 480, are blocked fromrotation. Thus, the coupling assembly 412 of this invention prevents therotation of the drive shafts 414 and 426 when the assembly is in theaccessory load state. Since the drive shafts 414 and 426 are unable torotate, this assembly 412 likewise is designed to prevent an accessory40 seated in the output drive shaft 426 from being rotated when theassembly is in the accessory load state.

[0186] Another feature of coupling assembly 412 is that actuator teeth518 a and 518 b are of unequal size. Normally, when the actuator 510 ismoved forwardly, the tips of teeth 518 a and 518 b will strikediametrically opposed surfaces of the adjacent teeth 502. However, dueto manufacturing tolerances, there is a remote possibility that the tipsof teeth 518 a and 518 b could strike adjacent beveled surfaces of theopposed teeth 502. If teeth 518 a and 518 b were to strike thesesurfaces simultaneously, the actuator 510 would be locked out fromfurther forward motion relative to the pusher ring 498. The actuator 510would be prevented from driving the rest of the coupling assembly 412into the release. However, since tooth 518 b is longer than tooth 518 a,tooth 518 b is the first tooth to strike the beveled surface of anadjacent tooth 502. The continued forward movement of the tooth 518 bcauses sufficient rotational movement of the pusher ring 498 to ensurethat tooth 518 a then strike a beveled surface of the complementarypusher ring tooth 502 that is diametrically opposed to the surfaceagainst which tooth 518 b abuts. Thus, this feature of assembly 412prevents the assembly of inadvertently being locked out from beingdisplaced into the accessory load state.

[0187] It should also be understood that the same set of cuttingaccessories 40 that have shafts 44 of a common length that are used withattachment 36 may be used with attachments 170, 320 and 410. Thisfeature of the system 30 of this invention further minimizes the numberof different types of accessories 40 that need to be provided.

[0188] FIGS. 36-39 depict an alternative shaft 44 a of the cuttingaccessory 40 of this invention. Shaft 44 a includes the previouslydescribed main body 152 that extends rearwardly from attachment head 42.A stem 154 a extends coaxially rearwardly from main body 152. Thesection of the stem 154 a adjacent the main body 152 has a circularcross sectional profile that has a diameter less than the diameter ofthe main body 152.

[0189] The section of the stem 154 a distal from the main body 152,section 528, is shaped to have the retention features of the shaft 44 a.More particularly, section 528 of the stem 154 a is shaped so as to havea plurality of diametrically opposed concave faces 530 that extendinwardly from the outer surface of the section of the stem adjacent themain body. The faces 530 are in two sets. In each set, the faces arelongitudinally aligned and longitudinally spaced apart from each other.

[0190] It will be observed that shaft section 528 is formed so theslices of the section where diametrically opposed adjacent pairs offaces 530 meet are asymmetrically formed relative to the longitudinalaxis of the shaft 44 a. For example, in the depicted embodiment of theinvention, as seen in FIG. 38, the slice of the shaft section where thetwo faces 530 a and 530 b in the top of the drawing closest to main body152 is formed to have a flat surface 532. Opposite flat surface 532, theportion of section 528 that forms faces 530 d and 530 e, the facesdiametrically opposite faces 530 a and 530 b, respectively, is shaped todefine a line-shaped crest 534. Crest 534, as best seen in FIG. 39,projects further away from the longitudinal axis of stem 154 a than thedistance flat 532 extends from the same axis. The crest 534 can beconsidered to be formed by the ends of adjacent faces 530 d and 530 e.

[0191] Extending distally along stem 154 a, it will be seen that betweenthe second and third top-located faces, faces 530 b and 530 c, section528 is formed to have a crest 534. Diametrically opposite this crest534, in the slice space between downwardly directed faces 530 e and 530f, there is a flat 532. Thus, on one side of section 528 the slicesbetween the faces are shaped to have an alternatingflat-crest-flat-crest pattern; on the opposite side of the section theslices are shaped to have an alternative crest-flat-crest-flat pattern.

[0192] It will further be observed from FIGS. 37 and 38 that theproximal end tip of stem 154 a is formed to have two symmetricallyopposed beveled surfaces 535. Each surface 535 is in line with aseparate one of the sets of the linearly arranged faces 530. Surfaces535 function as tapered surfaces that allow the proximal end of the stem154 to be slip fitted between the collet feet 541, FIG. 40, internal tothe handpiece 32 with which the accessory of this invention is used.

[0193] As seen by reference to FIG. 40, a generic collet 540 of thecoupling assembly in which shaft 44 a is inserted is shaped to have feet541 with opposed toe surfaces 542 that face each other. Moreparticularly, the collet is shaped so that the toe surfaces 542 have aradius of curvature equal to the radius of curvature of the faces 530that form the retention features of the shaft 44 a. When the collet feet541 are pressed against the shaft section 528, and the collet toesurfaces 542 are seated in opposed faces 530, the collet feet clamp theshaft 44 a to the collet so that the collet and shaft will rotate inunison.

[0194] The reasons why slices of shaft section 528 are asymmetric formedis best understood by reference to FIGS. 40 and 41. Statistically, mostoften when the collet feet 541 pressed against stem section 528, the toesurfaces 542 strike the curved surfaces of a pair of diametricallyopposed faces 530. The continued urging of the collet feet 541 togethercauses a minor longitudinal displacement of the shaft 44 a. Thisdisplacement occurs until the collet toe surfaces 542 are pressedagainst the shallowest sections, the troughs, of the opposed faces 530.

[0195] However, due to manufacturing tolerances, if the cuttingaccessory is formed to have opposed crests 534, these crests may not beprecisely aligned. In some instances, as illustrated in FIG. 41, whenthe collet feet 541 are moved together, depending on the position of thetoe surface 542 relative to the crests, the feet could bind theaccessory shaft. Once the shaft is so caught, the collet feet 541 are nolonger able to displace, auto-align, the shaft so that the toe surfacesseat in the troughs of one of the pairs of faces 530.

[0196] The provision of the asymmetrically shaped sections betweenadjacent pair of longitudinally spaced apart faces 530 in the shaft ofthis invention substantially eliminates the likelihood that the aboveevent can occur. With shaft 44 a, when collet feet 541 move towards asection between the faces 530, the toe surface 542 of one foot strikesthe adjacent shaft crest 534 before the opposed toe surface strikes thecomplementary flat 532. As a result of the one collet foot 541 strikingthe crest 534 without an opposing contact occurring, the shaft islongitudinally displaced as represented by curved arrow 546 in FIG. 42.This longitudinal displacement of the shaft 44 a longituinally alignsthe shaft with the collet 540 so that the collet feet 541 will then bearagainst diametrically opposed shaft faces 530. Thus, the asymmetricshaping of the shaft 44 a facilitates the longitudinal auto-alignment ofthe shaft with the coupling assembly in which the shaft is inserted.

[0197] Still another feature of shaft 44 a, is that there are no largeconstant diameter sections between adjacent retention features.Consequently there is no likelihood that the grasping members of acoupling assembly could inadvertently hold one of these inter-retentionfeature sections and give a false feel to surgical personnel that theshaft is clamped in place when, in fact, it is not so securely held.

[0198] It should be recognized that the above-described version of theshaft may vary from what has been described. For example, in thedescribed version, the retention features are diametrically opposedfaces that are circumferentially spaced apart from each other. In otherversions of the invention the retention features may circumferentiallyabut each other.

[0199] Also, in other versions of the invention, on each section of theshaft 44 a on which the retention features are formed there may be morethan the two retention features shown in the illustrated embodiment ofthe invention. Similarly, in some versions of the invention, theretention features may comprise a single set of longitudinally linearlyaligned faces that extend down the length of one arcuate portion of theshaft stem. It should likewise be recognized that, in the auto alignmentprocess, depending on the position of the shaft 44 a relative to thecollet 540, there may be situations in which as the collet feet pressagainst the shaft, the shaft is displaced in a direction opposite thedirection depicted in FIG. 42.

[0200] Similarly, it should be recognized that the surface geometry ofthe disclosed retention features is understood to be exemplary, notlimiting. For instance it may be desirable to form some retentionfeatures so that their surfaces have both curved and planar sections orwholly planar sections. For example, in some versions of the invention,each retention feature may be a pair of angled faces formed in the shaftstem. Collectively, the set of linearly arranged retention featureswould have a sawtooth pattern.

[0201] Also, the lateral sections located between the longitudinallyspaced apart retention features may have different cross-sectionalgeometries that what has been illustrated. In some versions of theinvention, it may not even be necessary to provide the shaft stem withthe asymmetrically shaped sections between adjacent retention features.

[0202] Similarly, in some versions of the invention, it may be desirableto form the proximal end of the stem 154 a so that it has a geometrydifferent than the opposed beveled surfaces 535. For example, it may bedesirable to form this portion of the cutting accessory so that it has afrusto-conical shape. The inclined surface of this section would providethe same functional result as the beveled surface 535.

[0203] It should be understood that the foregoing description isdirected to specific versions of the surgical tool system 30 of thisinvention. Other versions of the invention may differ from what has beendescribed. For example, it may not always be necessary to form inputdrive shaft 336 out of two components as has been described. It should,of course, be understood that the ball bearing slots 286 and 384associated with attachments 170 and 320, respectively, are typicallyformed with tails so that coupling assemblies 176 and 334 can be lockedin the accessory load state. However, in some versions of the invention,the coupling assemblies may not be provided with means to be locked inthe accessory load state.

[0204] Moreover, the components forming the individually describedcoupling assemblies 38, 176, 334 and 412 nay be interchanged with eachother as necessary.

[0205]FIGS. 43 and 44 illustrate an alternative removable attachment 550of this invention. Attachment 550 includes a housing 552 and base 554similar, if not identical to previously described housing 48 and base56. A drive shaft 556 is rotatably fitted in housing 552 with a bearingassembly 560. A bearing retainer 562 holds the bearing assembly 560 inthe counter bore in which the assembly is seated. One or more shimwashers 563 may be fitted between the proximal end of bearing assembly560 and the adjacent surface of the housing 552 to account formanufacturing tolerances.

[0206] Drive shaft 556, seen best in FIGS. 45 and 46, has a proximal end564 with a hex shaped cross sectional profile for the purposespreviously described. Extending forward from the main cylindricalportion of the driver shaft, it is observed that the drive shaft isformed to have a circumferentially extending flange 566. The distal endof the drive shaft 556 is formed to have a round head 568 that has areduced outer diameter relative to the rain body of the drive shaft.

[0207] A constant diameter bore 569 extends axially through the driveshaft 556 from the distal front end of the head 568 to a positionslightly rearward of flange 566. The distal end of the main body of thedrive shaft 556, the portion located immediately rearward of head 568,is formed to have two diametrically opposed slots 570. Slots 570 areeach defined by a flat base and parallel side walls that extendperpendicularly upwards from the base. Drive shaft 556 is further formedto have a laterally extending channel 572 that extends between the slots570. Channel 572, it will be understood, also intersects bore 569.

[0208] A collet 578, seen best in FIG. 47, is fitted over the driveshaft 556. Collet has a ring-shaped base 580. When attachment 550 isassembled, the collet 578 is positioned so that base 580 is fitted overthe portion of the main body of the drive shaft 556 immediately distalto the head 568. Two diametrically opposed legs 582 extend rearwardlyfrom the base 580. Each leg 582 is seated in a separate one of the slots570. A foot 584 extends inwardly from the free end of each leg 582. Eachfoot 584 seats in a separate end of channel 572. Each foot 584 has a toesurface with a main section 586 that has a convex profile. Moreparticularly, the curvature of the toe surface main section matches thatof the faces 530 of the complementary shaft 44 a. Extending distallyfrom main section 586, the toe surface is shaped to form a notch 588that has a curved profile. The toe surfaces of feet 584 are seated inthe opposed ends of channel 572.

[0209] The outer surface of each foot 564 is shaped to have an ankle. Afirst part of the ankle, at the distal end of the associated foot 564,is a curved notch 590. Extending proximally, towards collet base 580,the ankle has a main surface 592 that forms the outer surface of thefoot 564. This ankle main surface is located inwardly of the outersurface of the associated collet leg 582. Between the main surface 592and the collet leg 582, the ankle has a beveled surface 594 that istransition surface between the main surface 592 and the leg 582.

[0210] A collet sleeve 596 is slidably fitted over the drive shaft 556adjacent the collet feet 584. The collet sleeve, as seen in FIG. 48, hasa circular base 598. Two diametrically opposed webs 602 extendproximally forward from the base 598. Each web 602 is formed to have arectangular tab 604 that extends inwardly towards the center axis of thesleeve 596. Each web 602 terminates at a head ring 606. The innerdiameters of sleeve base 598 and head ring 602 are identical. Head ring606 has an outer diameter that is greater than the outer diameter of thebase 598. Collet sleeve 596 is fitted to the drive shaft so that tabs604 seat in the portions of slots 570 that are located proximal tochannel 572.

[0211] A coil spring 610 pushes the collet sleeve 596 in the forwarddirection, towards collet feet 584. Spring 61O seats against the driveshaft flange 556. The proximal end of the spring 610 seats against alaterally extend circumferential step surface of the collet sleevebetween webs 602 and head ring 606.

[0212] Extending forward from housing 552, attachment 550 has a nosetube 614. The nose tube 614 has an outer surface that is generallycylindrical. Nose tube 614 is, however, formed to have an annular flange616 that is located forward of the distal end of the tube. When theattachment 550 is assembled, the portion of the nose tube 614 distal toflange 616 seats in the housing 552. Flange 616 seats against theproximal end of the housing 552. More particularly, nose tube 614 isdimensioned so that the distal end of the tube extends over the driveshaft head 568 and the adjacent portion of the main body of the driveshaft over which the collet base 580 is seated. The inner diameter ofthe nose tube 614, it is understood, is greater than the outer diameterof the drive shaft 556. A bearing assembly 618 provides a low-frictioninterface between the drive shaft head and the adjacent inner surface ofthe nose tube 614.

[0213] Inside nose tube 614, forward of bearing assembly 618 are a pairof preload rings 620. The preload rings are held apart by a tube-shapedpreload spacer 622. Forward of the most proximal preload rings 620 arefour bearing assemblies 234. A tube-shaped bearing spacer 624 ispositioned between the second and third bearing assemblies 234. Shims626 are located adjacent some of the bearing assemblies 234. It shouldalso be recognized that there might be some variations in the individualbearing assemblies 234. For example, when two bearing assemblies 234 areadjacent, one of the bearing assemblies may have an inner race that isslightly longer in length than the complementary outer race. Thiscomponent selection is to ensure proper loading of the bearingassemblies and the other components and/or to prevent contact betweenopposed races adjacent bearing assemblies.

[0214] A coil spring 628 extends around preload spacer 622. Spring 628biases the distal preload ring 620 and the components forward thatpreload ring in the forward direction. Movement of these componentsinternal to the nose tube 614 is stopped by the abutment of the forwardmost bearing assembly 234 against an annular step internal to the nosetube 614.

[0215] A rotating collar 632 and an actuator 634 cooperate toselectively displace urge the collet sleeve 586 rearwardly away from thecollet feet 584. Actuator 634 is generally ring shaped and extendsaround the collet legs 582 and the adjacent portion of the drive shaft556. Actuator 634 is formed with diametrically opposed indentations 636designed to accommodate complementary ball bearings 126. The ballbearings 126 extend through slots 638 formed in the housing 556 that aresimilar to slots 124 of housing 48.

[0216] Collar 632 is rotatably fitted over the portion of the housing552 in which slots 638 are formed. The collar is formed with opposedgrooves 640 that have an arcuate cross section profile. When the collaris fit over housing, the sections of ball bearings 126 that extendbeyond slots 638 seat in grooves 640. A collar ring 642 is threadedsecured to the section of the housing 552 that is forward of collar 632.Collar ring 642 thus releasably holds the collar 632 over the housing552. The proximal end of collar ring 642 has an inwardly directedannular step 644. When collar ring 642 is secured to the housing 552,step 644 bears against the forward facing surface of nose tube flange616 so as to hold the nose tube 614 to the housing.

[0217] A coil spring 646 acts against actuator 634 to ensure that theactuator 634 is normally spaced from the collet sleeve 596. One end ofspring 646 bears against the outer race of bearing assembly 560, racenot identified. The opposed end of spring 646 bears against the proximalend of a spacer ring 648. The distal end of spacer ring 648 bearsagainst actuator 634.

[0218] In the absence of external force, spring 646 and spacer ring 648cooperate to hold actuator 634 away from collet sleeve 596. When thecoupling assembly of attachment 550 is in this state, spring 610 pushesthe collet sleeve 596 in the forward direction. As a result of thispositioning of the collet sleeve 596, the portions of the sleeve webs602 forward of the tabs 604 bear against the collet ankle main surfaces592. The forward movement of the collet sleeve 596 is stopped by theabutment of the sleeve tabs 604 against the bottom, rearwardly facingsurfaces of the collet feet 584. When the coupling assembly is in thisstate, the accessory run state, movement of the collet toe sections outof drive shaft bore 569 is blocked. Thus, the collet feet 584 will beeragainst the opposed faces 530 of the cutting accessory shaft 44 a seatedin the bore 569. This action ensures that the cutting accessory shaft 44a will rotate in unison with the rotation of the drive shaft.

[0219] The coupling assembly is displaced from the accessory run stateto the accessory load state by the manual rotation of collar 632. Thismovement causes the helical displacement of ball bearings 126 in slots638. The longitudinal rearward displacement of the ball bearings 126results in a like displacement of actuator 634. As a result of themovement of the actuator 634 to the distal end of the attachment 550,the distal end face of the actuator abuts the adjacent proximal end faceof the collet sleeve 596. The continued movement of the actuator 634results in the actuator overcoming the force of spring 610 and movingthe spring distally, away from the collet feet 582. Thus, when thecoupling assembly is in this state collet feet 582 are free to flexoutwardly away from shaft bore 569. Thus, when the coupling assembly isin this state the stem 154 a of the cutting accessory can be removedfrom the shaft bore 569, inserted into the shaft bore, or its positionselectively set in the shaft bore.

[0220] An alternative angled attachment 650 of this invention is nowdescribed by initial reference to FIGS. 49 and 50. Angled attachment 650includes base 554 to which an angle housing 652 is attached. Anglehousing 652 has a main body 654 that is coaxial with base 554. Forwardfrom main body 654, angle housing 652 is shaped to have a constantdiameter neck 656. Neck 656 is axially offset from main body by anglebetween 15 and 45°. Attachment 650 also has an elongated generallycylindrical front housing 657. The distal end of front housing 657extends over and is threadedly secured to the outer surface of anglehousing neck 656. Front housing 657 thus extends coaxially forward fromneck 656.

[0221] An input drive shaft 658 is rotatably mounted in angle housingmain body 654. Two bearing assemblies 560 rotatably hold the input driveshaft to the angle housing 652. A proximal one of the two bearingassemblies 560 is seated in the base of a counterbore 660 formed in themain body 654. A distal one of the bearing assemblies 560 extendsbetween the drive shaft 658 and the wall at the distal end of thecounterbore 660. A tube-shaped spacer 662 holds the bearing assemblies560 apart from each other. Bearing retainer 562 holds the bearingassemblies 560 and the spacer in the angle housing 652. Shims 563 may belocated between the distal bearing assembly 560 and the surface ofhousing 652 against which the assembly seats.

[0222] The input drive shaft 658 is formed with a proximal end 664 thathas a hex-shaped profile. Input drive shaft 658 also has a largediameter head 668 that is located forward of the distal bearing assembly560. Head 668 is formed with gear teeth 670 that extend axially forward.In order to prevent longitudinal movement of drive shaft 658, atube-shaped lock ring 672 is press fit over the shaft 658. Moreparticularly, lock ring 672 is positioned to bear against the inner raceof the proximal most bearing assembly 560. Lock ring 672 thus preventsunwanted forward movement of the input drive shaft.

[0223] A transfer gear 676 and an output drive shaft 678 are rotatablyfitted to the angle housing neck 656 to transfer the rotational momentapplied to the input drive shaft 658 to the cutting accessory 40 fittedto attachment 650. The transfer gear 676, seen in FIG. 51, has a largediameter base 680. Base 680 has rearwardly extending teeth 682. Transfergear teeth 682 engage input drive shaft teeth 670 so the rotation of thedrive shaft 658 results in the like movement of transfer gear 676.Transfer gear 676 is further formed to have a reduced diameter stem 684that extends axially forward of base 680. The stem 684 is formed to havean axially extending circular bore 686, shown in phantom, that extendsrearwardly from its proximal end. Located distal to and contiguous withbore 686, an axially extending rectangular bore 688 is formed in stem.For manufacturing reasons, in the depicted version of the invention bore688 is seen as a rectangular slot that extends through opposed sides ofthe stem.

[0224] Two spaced apart bearing assemblies 690 rotatably hold transfergear 676 in angle housing neck 656. Both bearing assemblies 690 extendbetween the transfer gear stem 684 and the adjacent inner wall of theneck 656. A first bearing assembly 690 has an inner race, notillustrated, that seats against a shoulder surface between base 680 andstem 684. A second bearing 690 assembly is fitted around the proximalend of stem 684. A tube-shaped spacer 692 holds the bearing assemblies690 apart. A C-shaped retaining ring 694 holds the transfer gear 676,the bearing assemblies 690 and spacer 692 in neck 656. Moreparticularly, retaining ring 694 is snap fitted in a groove 696 formedin the inner wall of neck 656. One or more shims 697 may be providedbetween bearing assemblies 690 and the members adjacent the bearingassemblies 690.

[0225] The output drive shaft 678 is formed to have a tail 702 ofrelatively small diameter. The proximal end of the tail 702, which isthe proximal end of the outer drive shaft 678, has two diametricallyopposed flats 704. More particularly, the proximal end of the tail isformed to be press fit into bore 688 of transfer gear 676 so that thedrive shaft 678 and transfer gear are essentially a single unit.Extending forward from tail 702, output drive shaft 678 has a main body706. A circular flange 707 extends around the outer surface of the mainbody 706 a small distance forward of tail 702. A reduced diametershoulder section 708 is located forward of the main body 706. A head710, with a diameter less than that of shoulder section 708, forms theproximal end of the output drive shaft 678.

[0226] A bore 712 extends axially rearwardly from head 710. Opposedslots 714 are formed in the shaft main body 706 and shoulder sections708. A channel 716 extends laterally through the main body. Bore 712,slots 714, and channel 716 are geometrically similar to bore 569, slots570 and channel 572 of previously-described drive shaft 556.

[0227] Collet 578 is fitted over the proximal end of output drive shaft678. Collet feet 584 thus seat in the opposed ends of channel 716.Collet sleeve 596 is slidably fitted over the shaft main body 706rearwardly of the collet feet 584. Spring 610 extends between shaftflange 707 and the collet sleeve 596.

[0228] Front housing 657 it should be understood has a main section 720and a shoulder section 722 that is coaxial with the main section 720.Main section 720 is the portion of the front housing 657 that isthreadedly secured to angled housing neck 656. Front housing shouldersection 722 encases the forward portion of the output drive shaft 678,collet 578, collet sleeve 596 and spring 610.

[0229] Nose tube 614 extends forward from the proximal end of fronthousing shoulder section 722. Nose tube flange 616 seats against anadjacent proximal end surface of the front housing shoulder section 722.Previously described preload rings 620, preload spacer 622, spring 628,bearing assemblies 234, bearing spacer 624 and shims 626 are fitted inthe nose tube 614.

[0230] Collar 632 is fitted over the front housing 657 and actuator 634is disposed in the front housing in order to selectively displace colletsleeve 596. Actuator 634 is fitted around the portion of the outputdrive shaft 678 over which the collet legs 582 are seated. A spring 724and spacer ring 648 are provided in order to ensure that actuator 634 isnormally spaced away from collet sleeve 596. Spring 724 extends betweenthe outer race of the proximal bearing assembly 690, outer race notillustrated, and spacer ring 648.

[0231] Collar 632 is rotatably fitted to the front housing shouldersection 722. Ball bearings 126 transfer the rotational movement of thecollar 632 to the actuator 634. In order for the collar's movement to betransferred to the actuator as helical movement, the ball bearings 126extend through slot 726 formed in the housing shoulder section 722.Slots 726 are similar in shape to slots 638.

[0232] Collar ring 642 is threaded to the proximal end of the fronthousing 722 to secure the nose tube 614 and collar 632 to the fronthousing 722.

[0233] The coupling assembly internal to attachment 650 works in thesame general manner as the coupling assembly internal to attachment 550.Collet sleeve 596 normally presses against collet feet 584. Thisinteraction holds the collet feet 584 in bore 712 of the output driveshaft 678. Thus, the collet feet 584 hold the associated shaft 44 a inthe bore 712 so that the cutting accessory shaft 44 a rotates in unisonwith the output drive shaft 678. The rotation of collar 632 results inthe longitudinally displacement of the collet sleeve 596 away from thecollet feet 584. When the collet sleeve 596 is so positioned, the colletfeet 584 are able to flex away from the output drive shaft to allow theremoval, insertion or repositioning of the cutting accessory in thedrive shaft bore 712.

[0234] Owing to its angled configuration, attachment 650 can, in somesituations, allow the surgeon to have a less-obstructed view of thesurgical site.

[0235] An alternative long attachment 740 of this invention is nowdescribed with initial reference to FIGS. 53 and 54. Long attachment 740includes a housing 742 to which base 554 is attached Housing 742 issimilar to housing 552 except for one significant difference which isdiscussed below. An elongated nose tube 743 extends forward from thedistal end of housing 742. Bearing assembly 560 rotatably holds an inputdrive shaft 744 in housing 742. Bearing retainer 562 holds bearingassembly 560 in position.

[0236] As seen best in FIGS. 54 and 55, input drive shaft 744 includes aproximal end 746 with a hex shaped profile. The distal end of shaft 744has a head 748 with a relatively large diameter relative to the rest ofthe shaft. An axially extending bore 750 extends rearwardly from thedistal end of the head 748. Input drive shaft 744 is further formed tohave an elongated slot 752 that is located a slight distance rearwardlyfrom the distal end of the head. Slot 752 extends laterally throughshaft 744 and intersects bore 750.

[0237] A push rod 756 is seated in shaft bore 750. As seen best in FIGS.57 and 58, push rod 756 is formed to have a cylindrical main body 758that has a relatively wide diameter. A cylindrical neck 760 of narrowdiameter extends coaxially forward of the main body 758. The main body758 is formed to have two diametrically opposed flats 762. A small bore764 is formed in the proximal end of the main body. Push rod neck 760 islikewise formed so that the distal end thereof has two opposed flats766. The planes in which flats 766 are oriented are parallel to theplanes in which flats 762 are oriented. A bore 768 extends rearwardly ashort distance through the forward facing distal end face of push rod756.

[0238] Shaft bore 750, shaft slot 752 and push rod flats 762 arecollectively dimensioned so that the proximal end of the push rod 756 isslidably fitted in the bore 750 and slot 752. Input drive shaft 744 andpush rod 756 are further dimensioned so that, when the proximal end ofthe rod is seated in the drive shaft, the two components engage in likerotation. Bearing assemblies 234 rotatably hold push rod 756 in theproximal end of nose tube 743. A spacer 755 separates the bearingassemblies 234.

[0239] Located within the base of shaft bore 750 is a T-pin 770. Thelongitudinal cross bar of T-pin 770, bar not identified, is dimensionedto extend through and is slidably fitted in the opposed open ends ofslot 752. The center post of T-pin 770, post not identified, is securelypress fit into proximal end bore 764 of the push rod 756. A small spring773 is seated in the base of shaft bore 750. Spring 773 pushes againstT-pin 772 so as to urge the T-pin and push rod 756 in the forwarddirection. T-pin 770, as discussed below, is used to affect thelongitudinal displacement of the push rod 756.

[0240] Push rod 756 rotates an output drive shaft 774 that is rotatablyfitted in the nose tube 743. The output drive shaft 774, as seen inFIGS. 58 and 59, has a cylindrical main body 776. A cylindrical head778, with an outer diameter greater than the diameter of the main body774 extends axially forward from the main body. The proximal end of themain body 776 has a forwardly extending bore 780. The main body 776 isfurther formed have an elongated slot 782 that is located forward ofbore 780. Bore 780 and slot 782 are contiguous. Located forward of slot782, the output drive shaft 774 is formed to have An outwardly extendingcircumferentially extending flange 784. Flange 784 is formed to have twospaced arcuately spaced apart sections so as to define cutout spaces 786between the flange sections.

[0241] The output drive shaft 774 is formed so that its most distalsection is a nose 788. The nose 788 is coaxial with and has a smallerouter diameter than head 778. A bore 790 extends axially rearwardly fromthe front end of the shaft nose 788, through the head and into thedistal portion of the main body 776. The proximal end of the shaft head778 is formed to have diametrically opposed openings 792 adjacent head778. openings 792 are contiguous with bore 790.

[0242] Bearing assemblies 234 rotatably hold the output drive shaft 774in nose tube 742. A first bearing assembly 234 is fitted over theproximal end of the drive shaft 774. A ring shaped bearing spacer 794located immediately forward of the proximal bearing assembly 234 extendsaround the output drive shaft 774. Spacer 794 prevents the proximalbearing assembly 234 and the output drive shaft 774 from moving relativeto each other. A retaining ring 791 holds spacer 794 in place. It willalso be observed that there is a spacer 755 located between the bearingassembly 234 associated with the proximal end of the output drive shaft774 and the adjacent bearing assembly 234 associated with the push rod756.

[0243] The distal bearing assembly 234 extends between the shaft nose788 and the adjacent inner wall of nose tube 743. Shims 775 separate thedistal bearing assembly 234 from an adjacent pre-load ring 620 in thenose tube 743.

[0244] When the drive shaft 774 is seated in the nose tube 743, push rodneck 760 is seated in shaft bore 780 and slot 782. Push rod 756 andoutput drive shaft 774 are collectively dimensioned so that the twocomponents will rotate in unison and the push rod is able to movelongitudinally within the shaft bore 780 and slot 782.

[0245] A cross pin 798 is seated in shaft bore 780. The cross pin 798rests on the distal end surface of the push rod neck 760. The cross pin798 is dimensioned so that its opposed ends extend out of shaft slot782. Cross pin 798 is further formed so at each end there is a forwardfacing finger 800.

[0246] A collet 802 is fitted around the output drive shaft 774. Thecollet 802, now described by reference to FIG. 60, includes a circularbase 804 from which two diametrically opposed legs 806 extends. A foot808 extends inwardly from each leg 806. Each foot 808 has a toe surface810 located proximal to the longitudinal axis of the collet 802 and anankle 812 distal from the axis. Collet feet 808 toe surfaces 810 andankles 812 have the same surface geometry as the toe and ankle surfacesof collet feet 584.

[0247] Collet 802 is fitted around the output drive shaft 774 so thatbase 804 abuts the rearwardly facing face of flange 784. The collet legs806 extend in the forward direction so that the legs extend throughspaces 786. Collet feet 808 thus seat in shaft openings 792. When thecollet feet 808 are so seated, the toe surfaces 810 are located withinshaft bore 790.

[0248] A tube shaped collet sleeve 814 regulates the ability of thecollet feet 808 to flex away from the shaft bore 790. As seen in FIG.61, the collet sleeve is shaped so that immediately forward of theproximal end there are two diametrically opposed openings 816 that haveapproximately a rectangular cross sectional profile. Rearward of thedistal end of the sleeve 814 there are two diametrically opposedelongated openings 818. Each opening 816 is longitudinally aligned witha separate one of the openings 818. The distal end of the collet sleeve814 is formed to have an annular lip 817 that extends inwardly towardsthe longitudinal axis of the sleeve.

[0249] The collet sleeve 814 slidably fits over the collet 802 and theoutput drive shaft 774. More particularly, it will be observed that whenattachment 740 is assembled, fingers 800 of cross pin 798 each seat inan opposed one of the openings 816. The cross pin 798 thus transfers therotational moment of push rod 756 to the collet sleeve 814. The colletsleeve 814 is further aligned so that collet legs 806 and ankles 812 aredisposed within sleeve openings 818.

[0250] A coil spring 820 located between the collet 802 and the colletsleeve 814 urges the sleeve in the rearward direction. The distal end ofspring 820 seats against the rearward facing annular surface of thecollet base 804. The proximal end of the spring 820 presses against apilot ring 822 that is fitted around the outside of the proximal end ofthe output drive shaft 774. The rearwardly directed face of pilot ring822 bears against the forward facing portions of the cross pin 798 bodythat extend beyond the perimeter of the output drive shaft 774.

[0251] An actuator 826 disposed inside housing 742 is displaced in orderto force like longitudinal displacement of the collet sleeve 814 awayfrom the collet feet 808. Actuator 826 is generally similar to actuator634. However, actuator 826 is longer in height than actuator 634.Actuator 826 is also formed with a pair of forward facing, diametricallyspaced apart teeth 828.

[0252] Attachment 740 is also provided with collar 632. The collar 632is rotatably fitted to a constant diameter section of housing 742. Ballbearings 126 are seated in helical slots 830 formed in the housing.Slots 830 are similar to slots 638. However, slots 638 are designed sothat clockwise rotation of collar 632 results in rearward displacementof the ball bearings and actuator 634. Slots 830 are shaped so that thesame motion of collar 632 of attachment 740 results in forwarddisplacement of the ball bearings 126 and actuator 826.

[0253] A coil spring 832 extends around the proximal end of input driveshaft 744. Spring 832 is seated against an annular step at the base of acounter bore inside housing 742. Spring 832 bears against actuator 826so that the actuator is normally held away from T-pin 770.

[0254] Preload rings 620, spring 628 bearing assemblies 234, bearingspacer 624 and shims 62 are fitted in nose tube 743. A preload spacer622 a, which may be slight longer than preload spacer 622 is locatedbetween preload rings 620.

[0255] In the absence of external force, spring 820 pushes pilot ring822 and the cross pin 798 rearwardly. The rearward displacement of thecross pin 798 results in a like motion of push rod 756 and collet sleeve814. As a result of the rearward displacement of the collet sleeve 814,sleeve lip 817 abuts complementary surfaces in the collet feet ankles812. This contact holds the collet feet 808 in bore 780 of the outputdrive shaft 774. Thus, when the collet feet 808 are so locked inposition they hold any cutting accessory 40 fitted in the bore to thedrive shaft 774 so that the accessory rotates with the drive shaft.

[0256] Spring 832 normally holds the actuator 826 away from T-pin 770.Thus spring 832 prevents the actuator from inadvertently contact theT-pin that could, in turn, result in the displacement of the colletsleeve 814.

[0257] Collar ring 642 secures collar 632 and nose tube 743 to thehousing.

[0258] When it is desired to place attachment 740 in the accessory loadstate, collar 632 is rotated. The rotation of the collar 632 causes theactuator 826 to overcome the force of spring 832 and move in the forwarddirection. As a result of its forward displacement, actuator 826eventually strikes the opposed end portions of T-pin 770 that extendbeyond the outside of input drive shaft 744.

[0259] The continued forward movement of the actuator 826 causes theactuator to force the T-pin 770, and therefore push rod 756, in theforward direction. The forward displacement of the push rod 756 resultsin the like displacement of cross pin 798. The forward movement of thecross pin 798 causes the collet sleeve 814 to engage in a likelongitudinal transition. As result of the longitudinal transition of thecollet sleeve 814 relative to the output drive shaft 774, the sleevewindows go into registration with the collet feet 808. When theattachment 740 is in this state, the accessory load state, the colletfeet 808 are free to flex out of the bore 790 of the output drive shaft.This makes it possible for an accessory 40 to be removed from, insertedin or adjustably positioned in the output drive shaft 774.

[0260]FIGS. 63, 64 and 65 illustrate an angled long attachment 840 ofthis invention. Attachment 840 includes housing 652, input drive shaft658, transfer gear 676 and the associated components used to hold thedrive shaft and gear in position.

[0261] An elongated push rod 842 extends forward from transfer gear 676.The proximal end of push rod 842 is formed with flats 841. Consequently,when the proximal end of the push rod 842 is fitted in the transfer gearbore 688 the push rod both rotates in unison and is able to movelongitudinally relative to the transfer gear 676.

[0262] A front housing 846, similar to front housing 657, extendsforward from angle housing neck 656. Push rod 842 is substantiallylocated in front housing 846. A bearing assembly 844 rotatably holds theproximal end of the push rod in front housing 846.

[0263] Nose tube 743 extends forward from the front end of front housing657. The nose tube 743 surrounds the forward portion of push rod 842. Abearing assembly 234 provides a low friction interface between the pushrod 842 and the adjacent inner surface of nose tube 743.

[0264] Previously described output drive shaft 774, collet 802 andcollet sleeve 814 are rotatably mounted in nose tube 743. Whenattachment 840 is assembled flats located at the distal end of the pushrod, flats not identified seat in bore 780 of the output drive shaft774. Collectively, the drive shaft 774 and the push rod 842 are formedso that rotation of the push rod will cause like motion of the outputdrive shaft and the push rod is able to move relative to longitudinallyfixed drive shaft.

[0265] A tube-shaped spacer 848 is also seated in the proximal end ofnose tube 743. Spacer 848 serves to hold the bearing assembly 234 fittedto the push rod 842 and the bearing assembly fitted to the proximal endof the output drive shaft 774 apart from each other. Shims 850 areprovided to accommodate for manufacturing tolerances.

[0266] It will further be observed that a small sleeve 854 is pressfitted or otherwise securely fitted to push rod 842. Sleeve 848 is shapeto define a small, rearwardly directed annular chamber 849 between aninner wall of the spring and the outer surface of the push rod 842. Acompression spring 850 is seated in chamber 849. Spring 850 worksagainst bearing assembly 844 to impose a small forward force on sleeve848 and push rod 842.

[0267] Actuator 634 is disposed around the push rod 842 and is locatedrearwardly of sleeve 848. Collar 632 extends around a constant diametersection of front housing 846. Ball bearings 126, seated in front housingslots 854 couple the actuator 634 to the collar 632. Slots 854 aredimensioned so that the manual rotation of the collar 632 results in theforward displacement of the actuator 634.

[0268] A spring 856 is located around sleeve 848. The distal end ofspring 856 is seated against an annular step formed inside front housing846. The distal end of spring 848 works against spacer ring 648 thatabuts the forward facing face of the actuator 634.

[0269] When attachment 840 is in the run state, spring 820 generates theforce that serves to position the collet sleeve 814 of the collet ankles812. Spring 856 prevents the unintended forward movement of the actuator634.

[0270] Attachment 840 is placed in the accessory load state by therotation of collar 632. The rotation of the collar 632 results in theforward movement of actuator 634. Eventually, actuator 634 abuts anoutwardly extending lip 858 integral with sleeve 848. Thus, as theactuator 634 continues to move forward, it pushes sleeve 848 and,therefore push rod 842, in the same direction. The forward displacementof the push rod 842 results in the like translation of the collet sleeve814 away from collet ankles 812. Once the collet sleeve 814 and colletankles 812 are so positioned relative to each other, an accessory 40 canbe removed replaced or reset as previously described.

[0271] In the described version of the system of this invention theoverall length of attachment 740 may be 2.5 cm or more than the lengthof attachment 550. In still other versions of this invention, thisdifference in length may by 3.5 cm or more or even 4.5 cm or more. Thisdifference in length is primarily because nose tubes 614 and 743 ofattachments 550 and 740, respectively, are of different length.(Housings 552 and 742 are of similar length.)

[0272] However, owing to the placement and dimensioning of thecomponents internal to the attachments 550 and 742, the levels at whichthe collet feet internal to the attachments grasp the complementaryaccessories 40 are substantially identical relative to the distal endsof the nose tubes 614 and 743. In some versions of the invention, thisdifference in distances relative to this most distal position along theattachments is 1.0 cm or less. In other versions of the invention, thedifference in distances is 0.5 cm or less. In preferred version of theinvention, this difference in distances is 0.25 cm or less. In stillother preferred versions of the invention, the distance between thedistal end of the attachments and the collet feet internal to theseattachments is the same regardless in variations in length betweenattachments.

[0273] An advantage of this arrangement is that cutting accessories 40having shafts of common length can each be used in each one of theattachments regardless of the difference in overall length between theattachments. Thus, this further minimizes the need to have a number ofdifferent cutting accessories available in which the only differencebetween the accessories is the length of their shafts.

[0274] It should also be understood that the arrangement of bearings inthe nose tubes minimizes the likelihood that lateral stress imposed onthe cutting accessories will result in either shafts biding against thenose tubes or “shaft whip” (the flexing back and forth of the shaft.

[0275] It should also be realized that the placement of the constructionof this invention makes it possible to provide nose tubes that have arelatively narrow outer diameter. In some versions of the invention,this diameter is less than 0.313 inches. In other versions of theinvention, this diameter is 0.260 inches or less. In other versions ofthe invention, this diameter is 0.240 inches or less. In even stillother versions of the invention, this diameter is 0.180 inches or less.In versions of this invention in which the nose tube bearings arereplaced by low friction bushings, it is anticipated that this diametermay be 0.13 inches or less. A benefit gained by this feature of theinvention is that the minimization in nose tube diameter increases thesurgeon's field of view.

[0276] Still another feature of this invention is that the rearwardfacing positioning of collet 578 in attachments 550 and 650 contributeto making it possible to using a single common collar 632 for each ofattachments 550, 650, 740 and 840. In many preferred versions of theinvention collar 632 has an outer diameter of 0.57 inches or less. Instill more preferred versions of the invention, this dimension is 0.4inches or less. An advantage of this construction of the invention isthat, by holding the diameter of the collar as well as the componentsdistal to this size, it further ensures that that the extent to whichthe attachment obstructs the surgeon's field of view is kept to aminimum.

[0277] Also, it should be realized that, in other versions of theinvention, one or more of coupling assemblies 38, 176, 334, and 412might not be built into a removable attachment. In these versions of theinvention, the coupling assembly may be integrally built into thesurgical handpiece designed to actuate the cutting accessories 40. Thesame is, of course true for attachments 550, 650, 740 and 840.

[0278] Furthermore, the shape of the various components of thisinvention may vary from what has been described. For example, thisinvention is not limited to collets that only have two feet. In someversions of the invention one or three more retractable members mayserve as the locking element or elements that grip the cuttingaccessory. It should likewise be recognized that the components of thevarious versions of the invention may be substituted with each other asnecessary. Members other than the described collets may be used as theholding members for releasably securing the cutting accessories to theattachments. These members include retractable tongues.

[0279] Similarly, the retention features 156 integral with the cuttingaccessory shaft 44 may have different profiles than described. Forexample, surfaces 160 and 162, instead of being straight, may be curved.The angle of surfaces 160 and 162, relative to faces 158 may be steep,for example, perpendicular, or shallow, greater than 135°. Also, thecross sectional profile of the faces forming the retention features maynot always be square. Clearly the size and shape of faces 158 may changewith the profile of the coupling assembly gripping surfaces intended toabut these faces. For the reasons set forth in U.S. Pat. No. 5,888,200,the retention features may be formed so that the edge corners where theretention features meet are differing distances from the longitudinalaxis of the shaft stem 154. Also, there is no requirement that, in allversions of the invention, the faces of the retention features berecessed relative to the outer surface of the shaft stem 154. In someversions of the invention, the retention features 156 may consist ofmembers that extend beyond the outer surface of the associated shaftstem 154.

[0280] Moreover, preload springs may be disposed within the head tubesof the attachments of this invention. As discussed in U.S. Pat. No.5,888,200, this type of spring imposes forces on the bearing assembliesinternal to the head tube so as to reduce bearing chatter.

[0281] Therefore, it is an object of the appended claims to cover allsuch modifications and variations as come within the true spirit andscope of this invention.

What is claimed is:
 1. A cutting accessory for a use with a surgicaltool, said cutting accessory including: a head; an elongated shaft thatextends from said head; and a plurality of retention features formed insaid shaft at longitudinally spaced apart locations along said shaft. 2.The cutting accessory of claim 1, wherein: said shaft is formed to have:a main body located adjacent said head, said main body having a firstcross sectional diameter; and a stem that extends from said main bodythat is spaced from said head and said stem has a second cross sectionaldiameter that is less than the first cross sectional diameter; and saidretention features are formed in said stem of said shaft.
 3. The cuttingaccessory of claim 2, wherein: said shaft is formed to have alongitudinal axis that extends coaxially through said main body and saidstem; and said stem is formed with laterally extending sections that arelocated between adjacent, longitudinally spaced apart retention featuresand said stem is formed so that the laterally extending sections betweensaid retention features are shaped asymmetrically relative to thelongitudinal axis of said shaft.
 4. The cutting accessory of claim 2,wherein said stem is formed with a plurality of linearly aligned,longitudinally spaced apart faces that extend inwardly relative to anouter surface of said stem and said faces are said retention features.5. The cutting accessory of claim 2, wherein said shaft is formed withlongitudinally spaced apart sets of inwardly directly faces, each saidset of faces comprising a plurality of faces that are arrangedcircumferentially around said shaft and each said set of faces forms onesaid retention feature.
 6. The cutting accessory of claim 1, wherein:said shaft has a longitudinal axis; and said shaft has laterallyextending sections that are located between adjacent, longitudinallyspaced apart retention features and said stem is formed so that thelaterally extending sections between said retention features are shapedasymmetrically relative to the longitudinal axis of said shaft.
 7. Thecutting accessory of claim 6, wherein: first and second longitudinallyspaced apart retention features are formed on a first arcuate section ofsaid shaft; third and fourth longitudinally spaced apart retentionfeatures are formed on a second arcuate section of said shaft wherein,the first and third retention features are laterally aligned with eachother and the second and fourth retention features are laterally alignedwith each other; the first and second retention features define a crestthat defines a first side of the laterally extending section, said crestbeing located a first distance from the longitudinal axis of said shaft;and a flat is located between the third and fourth retention featureswherein the flat is a second side of the laterally extending section andsaid flat is located a second distance from the longitudinal axis ofsaid shaft, the second distance being less that the first distance. 8.The cutting accessory of claim 1, wherein said shaft is formed withlongitudinally spaced apart sets of inwardly directly faces, each saidset of faces comprising a plurality of faces that are arrangedcircumferentially around said shaft and each said set of faces forms onesaid retention feature.
 9. The cutting accessory of claim 8, wherein thefaces forming each said set of faces are circumferentially spaced apartfrom each other.
 10. The cutting accessory of claim 8, wherein saidshaft of is formed so that each said set of faces comprises two facesthat are circumferentially spaced apart from each other.
 11. A cuttingaccessory for use with a surgical tool, said cutting accessoryincluding: a head; an elongated shaft that extends from said head, saidshaft having a longitudinal axis; first, second, third and fourthretention features formed on said shaft, wherein the first and secondretention features are longitudinally aligned with and longitudinallyspaced apart from each other, the third and fourth retention featuresare longitudinally aligned and spaced apart from each other, the firstretention feature is laterally aligned with and circumferentiallydisplaced from the third retention feature and the second retentionfeature is laterally aligned with and circumferentially displaced fromthe fourth retention feature; and a first lateral section formed in saidshaft at an interstitial location between the first and second retentionfeatures and the third and fourth retention features and said firstlateral section formed to have a first surface located between the firstand second retention features that is located a first distance from thelongitudinal axis of said shaft and a second surface located between thethird and fourth retention features that is located a second distancefrom the longitudinal axis of said shaft, the second distance being lessthan the first distance.
 12. The cutting accessory of claim 9, whereinsaid retention features are inwardly directed faces formed in saidshaft.
 13. The cutting accessory of claim 12, wherein said retentionfeatures are inwardly curved faces.
 14. The cutting accessory of claim11, wherein the first and third retention features are circumferentiallyspaced apart from each other and the second and fourth retentionfeatures are circumferentially spaced apart from each other.
 15. Thecutting accessory of claim 11, wherein said first lateral section isshaped so that at least one of the first or second surfaces of saidlateral section is a flat surface.
 16. The cutting accessory of claim11, wherein said first lateral section is shaped so that the firstsurface is a crest-shaped face located between the first and secondretention features and said second surface is flat face located betweenthe third and fourth retention features.
 17. The cutting accessory ofclaim 11, further including: a fifth retention feature formed on saidshaft, the fifth retention feature being longitudinally aligned with andlongitudinally spaced apart from the second retention feature and asixth retention feature formed on said shaft, the sixth retentionfeature being longitudinally aligned with and longitudinally spacedapart from the fourth retention feature and fifth retention feature islaterally aligned with the six retention feature; and a second lateralsection formed on said shaft at an interstitial location between thesecond and fifth retention feature and the fourth and sixth retentionfeature, said second lateral section formed to have a first surfacelocated between the second and fifth retention features that is locatedthe second distance from the longitudinal axis of said shaft and asecond surface located between the third and sixth retention featuresthat is located the first distance from the longitudinal axis of saidshaft.
 18. The cutting accessory of claim 11, wherein, said shaft isshaped to have: a main section that extends from said head, said mainsection having a first diameter; and a stem section that extends from anend of said main section distal from said head, said stem section havinga second diameter that is less than the first diameter and the retentionfeatures and said first lateral section are formed in said stem section.19. A cutting accessory for use with a surgical tool, said cuttingaccessory including: a head; a shaft that extends from said head, saidshaft having a longitudinal axis; at least two sets of retentionfeatures formed on said shaft, each set of retention features comprisingat least two longitudinally aligned, longitudinally spaced apartinwardly directed faces that are formed on said shaft wherein said setsof retention features are circumferentially offset from each otheraround said shaft and are aligned with each other so that each said faceof a first said set of retention features is laterally aligned with aface of a second said set of retention features; and at least onelateral section formed on said shaft, said lateral section being locatedbetween the longitudinally spaced apart, inwardly directed faces of saidsets of retention features and said lateral section is formed to have afirst surface located between the inwardly directed faces of the firstsaid set of retention features and a second surface located between theinwardly directed faces of the second said set of retention features andsaid lateral section is formed so that the first and second surfacesprovide said lateral section with an asymmetric cross sectional profilerelative to the longitudinal axis of said shaft.
 20. The cuttingaccessory of claim 19, wherein said sets of retention features arecircumferentially spaced apart from each other.
 21. The cuttingaccessory of claim 19, wherein: said shaft has two said sets ofretention features and said sets of retention features are diametricallyarranged relative to the longitudinal axis of said shaft; and saidlateral section is formed so that the first and second surfaces arediametrically arranged relative to the longitudinal axis of said shaft.22. The cutting accessory of claim 19, wherein said lateral section isshaped so that at least one of the first or second surfaces is a flatsurface.
 23. The cutting accessory of claim 19, wherein said lateralsection is shaped so that the first surface is crest-shaped face formedby said inwardly directed faces between which the first surface islocated and said second surface is flat face located between theinwardly directed faces adjacent the second surface.
 24. The cuttingaccessory of claim 19, wherein: each said set of retention featuresincludes at least three said inwardly directed faces that arelongitudinally aligned with and longitudinally spaced apart from eachother; and said shaft includes at least two said lateral sections,wherein: a first one of said lateral sections is located betweenadjacent first and second inwardly directed faces of said sets ofretentions features and is shaped so that the first surface of saidfirst lateral section is located between the first and second inwardlydirected faces of the first said set of retention features and thesecond surface of said first lateral section is located between thefirst and second inwardly directed faces of the second said set ofretention features; and a second one of said lateral sections is locatedbetween adjacent second and third inwardly directed faces of said setsof retentions features and is shaped so that second surface of saidsecond lateral section is located between the second and third inwardlydirected faces of the first said set of retention features and the firstsurface of said second lateral section is located between the second andthird inwardly directed faces of the second said set of retentionfeatures.
 25. The cutting accessory of claim 19, wherein said inwardlydirected faces have a curved profile.
 25. The cutting accessory of claim19, wherein, said shaft is shaped to have: a main section that extendsfrom said head, said main section having a first diameter; and a stemsection that extends from an end of said main section distal from saidhead, said stem section having a second diameter that is less than thefirst diameter and the retention features and said lateral section areformed in said stem section.
 27. A cutting accessory for use with asurgical tool, said cutting accessory including: a head; an elongatedshaft that extends from said head, said shaft having a proximal end thatis spaced from said head and at least one retention feature formed onthe proximal end of said shaft; and a coating disposed over said shaft,said coating being one from the group consisting of: titanium nitride;titanium aluminum nitride; titanium carbonitride; zirconium nitride;chromium nitride; and silicon nitride.
 28. The cutting accessory ofclaim 27, wherein said coating is disposed over said head.
 29. Thecutting accessory of claim 27, wherein said coating is not disposed oversaid head.
 30. The cutting accessory of claim 27, wherein said head andelongated shaft are formed from tool steel.